contents - doa.gov.lk · soils of sri lanka, plant nutrients, their role in plant nutrition,...
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ContentsCHAPTER I - Soils, soil formation and plant nutrients. ... 1
Section I - Soils ... 3Soils, major components of soils, properties of soils,physical, chemical & biological, nitrogen cycle,assignments.
Section II - Soil formation ... 9Rock weathering – physical & chemical, soil formingfactors, soil profile and different horizons, assignments
Section III - Soils of Sri Lanka ... 14Soils of sri Lanka, their fertility characteristics, soil map,assignments
Section IV - Plant nutrients ... 20Plant nutrients, essential nutrients, deficiency of anelement, toxic i ty, nutrient deficiency symptoms of crops,fate of nutrient elements in the soil, chemical fertilizers,organic manures, fertilizer use efficiency, assignments.
CHAPTER 2 - Balanced fertilizer use, soil testing,economics of fertilizer use ... 39
Section I - Importance of balanced fertilizer use ... 41Balanced fertilizer use, effect of unbalanced fertilization,effects of imbalanced use of chemical fertilizer onenvironment, Liebig’s law of minimum
Section II - Soil testing ... 45Soil sampling, laboratory analysis, plant analysis, fertilizerrecommendations, assignments.
Section III - Economics of fertilizer use ... 48Effect of fertilizer on yield, maximum yield and maximumeconomic yield, fertilizer application, cost of production& net profit, relation between economic yield & level ofmanagement, economics of nutrient use.
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CHAPTER 3 - Integrated use of organic manures andchemical fertilizers and principles. ... 53Integrated plant nutrition system, definition, objectives,farmer practices of IPNS, chemical fertilizers, organicmanures, organic farming versus IPNS, managing nutrientbalance in IPNS, socio economic side of IPNS, IPNS andenvironment, IPNS and FUE. IPNS practices for crops andcropping systems, assignments.
CHAPTER 4 - IPNS for Rice, Vegetables, OFC,Fruits Crops, Root and Tuber Crops ... 65
Section I - IPNS for Rice ... 67Introduction, nutrient removal in rice, present situation offertilizer use in rice cultivation, proven IPNS practices inrice production for the LCDZ, LCIZ, rice growingenvironments, associated problems in rice growing soils,cropping systems, recommended fertilizer practices,farmer practices in agro-ecological zones, assignments.
Section II - IPNS for Vegetables ... 81Introduction, vegetable growing eco-systems, nutrientmanagement in vegetable production, farmerpractices, vegetable based cropping systems,recommended practices, general farmer practices inagro-ecological zones, assignments.
Section III - IPNS for Chilli, Onion & Maize ... 891. Chilli – introduction, nutrient removal, chilli growing
environments,farmer practices, DOArecommendation, recommended organicmaterials usage, assignments.
2. Red Onion – Introduction, red onion based croppingsystems, proven IPNS used by farmers,recommended practices, assignments.
3. Big onion – Introduction, big onion based croppingsystems, recommended practices, assignments
4. Maize – Introduction, recommended practices,assignments.
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Section IV IPNS practices for fruit crops ... 101Introduction to fruit crop nature & characteristics
1. Banana – Current nutrients management practices,farmer practices, DOA recommendation, disadvantagesof current farmer practices, suggested IPNSprogrammes, assignments.
2. Papaya - Current nutrient management practices, farmerpractices DOA recommendation, suggested IPNSprogrammes, assignments.
3. Pineapple – Current nutrient management practices,farmer practices, DOA recommendation, suggestedIPNS programmes, assignments.
4. Passion fruit – Current nutrient management practices,farmer practices, DOA recommendation, suggestedIPNS programmes. assignments.
5. Citrus – Nutrient management practices farmerpractices, DOA recommendation, suggested IPNSprogrammes, assignments.
6. Rambutan – Farmer practices, DOA recommendation,suggested IPNS programmes, seedling / root stockplant production, assignments.
7. Mango – Current management practices, farmerpractices, DOA recommendation, suggested IPNSprogrammes.
Section V Root and Tuber Crops ... 121Introduction to root crops, nutrient removal1. Potato – Introduction, cropping systems, recommended
practices.2. Sweet potato – Introduction, cropping systems,
recommended practices.3. Innala - Introduction, cropping systems, recommended
practices.4. Manioc - Introduction, cropping systems, recommended
practices.5. Kiriala - Introduction, cropping systems, recommended
practices.6. Diascorea Yam - Introduction, cropping systems,
recommended practices.7. Ginger - Introduction, cropping systems, recommended
practices.8. Elephant Yam - Introduction, recommended practices,
assignments.
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List of Appendices
1 Deficiency and toxicity symptoms caused bydifferent nutrients in rice plant I
1a Deficiency symptoms caused bydifferent nutrients in Maize II
2 Fertilizer standards based on Sri LankaStandards Institute (SLSI) III-IV
3 Available plant species as green manurein the LCDZ and LCIZ V
4 Different types of livestock populationsin the country by districts VI
5 Organic materials and their nutrient composition VII-VIII
6 Agro - Ecological Regions of Sri Lanka IX-X
7 Nutrient removal by vegetablestotal and edible portion at harvest XI
8 Methods of Compost making. XII
9 Economics of IPNS XVIII
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List of abbreviations
AP & H Animal Production and Health
DOA Department of Agriculture
FAO Food and Agriculture Organization
IL Low country intermediate zone
IM Mid country intermediate zone
IPNS Integrated plant nutrition systems
IU Up country intermediate zone
LCDZ Low country dry zone
LCIZ Low country intermediate zone
NRMC Natural Resources Management Center
OFC Other field crops
TDM Top dressing mixture
WHO World Health Organization
WL Low country wet zone
WM Mid country wet zone
WU Up country wet zone
Soils, Soil Formationand Plant Nutrients
CHAPTER I
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This chapter deals with soilcharacteristics, weathering of rocks andsoil formation, profile characteristics,soils of Sri Lanka, plant nutrients, theirrole in plant nutrition, different types ofchemical fertilizers and organicmanures.
This chapter has thefollowing broad objectivesi. To provide knowledge on soils,
weathering of rocks, soilformation, profile characteristicsof soils and soil-plant nutritionrelationship.
ii. To provide information on soilsof Sri Lanka and their fertilitycharacteristics.
iii. To provide knowledge on plantnutrients, their characteristics,their role in crop growth, plantdeficiency symptoms, differentways of nutrient losses, sourcesof plant nutrients, chemical andorganic fertilizers, and fertilizeruse efficiency.
Section 1
SOILSWhat is soil?
l The uppermost crust of the Earth’ssurface which supports plant life.
l It is a product of rock weatheringand biological processes.
l It is composed of solid particles andpore spaces filled with air and soilwater between the particles.
l The constituents are mineral matter,water, air and organic matter bothliving and dead (Fig.1). The quantityof these constituents varies with thelocality.
l Climate, vegetation and man haveinfluenced the soil variations that arefound.
l It gives anchorage to plants and isa store-house for plant nutrients andwater.
SOLID PHASE PORE SPACE
Organic MatterWater AirMinerals
25%
25%
45%5%
Fig. 1. Major components of a typical soil
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Solid phase consists of
l Mineral constituents includingweathered rock fragments.
l Organic matter, both dead and livingmicro and macro organisms.
The mineral constituents are
Sand Large particles which are coarse,and individual particles are easilyvisible (0.02 – 2 mm in diameter)most common mineral componentis silica (SiO
2)
Silt Medium-sized particles whichare 0.002-0.02 mm in diameter
Clay Small particles which less than0.002 mm in diameter is referredto as colloids.
By definition, particles larger than sand arenot soil.
Liquid phase
l Soil water which occupies the porespaces (between mineral particles)carries the plant nutrients to the roots.
Soil air
l It occupies pore spaces similar tosoil water. It fills these voids whensoil water is absent.
l It carries respiratory products of rootsand soil-organisms.
l It has a higher concentration ofcarbon dioxide than atmospheric air.
Soil texture
l Refers to the relative proportion ofsand, silt and clay present in a soil.
l Based on these proportions soils areclassified into various texturalclasses.
l Clayey soils have a larger percent ofclay. They are considered more fertilethan sandy soils but are difficult towork.
l Sandy soils are easy to work but areless fertile. They have low waterretention capacity.
l Loamy soils are in between sandyand clayey soils. They are best forarable cropping.
Soil structure
l Refers to the arrangement of thedifferent particles into soilaggregates.
l Roots move between theseaggregates.
l A compact soil will resist rootmovement.
l The organic matter content helps thesoil aggregation process.
Soil type
l Soils are heterogeneous in nature.
l Heterogeneity depends on the natureof parent material and the externalfactors of climate, vegetation, aspectand time.
l Soils that are similar in physical andchemical characteristics are referredto as of the same soil type.
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Soil fertility
l Is the capacity of a soil to supplyplant nutrients in adequate amountsto facilitate optimum growth andobtaining the yield potential of a crop.
l Many soil properties determine theavailability of plant nutrients to plants.
SOME SOIL PROPERTIES THATDETERMINE SOIL FERTILITY
Soil colour
l Reddish to brownish colour showswell-drained conditions. Degree ofyellowness and mottling shows poordrainage. Gray to dark colourindicates the presence of organicmaterial.
Soil depth
l Refers to the depth to which plantroots can penetrate the soil and isthe distance between the lowest andthe upper most horizons of the soil.
Bulk density
l A compact soil has a higher valuewhile an organic soil has a lowervalue.
Water holding capacity
l Sandy soils have a low capacity thanclayey soils. This property isimportant for irrigation.
Field capacity
l Refers to the moisture content of asoil after the loss of gravitationalwater.
l At this point, water is held in soilmicropores, which is available toplant roots, until the water contentdown to a lower value.
l This lower value is referred to as thepermanent wilting point.
l The amount of water availablebetween field capacity andpermanent wilting point is referred toas available water.
l This value is important in determiningirrigation intervals.
Soil pH
l Is a measure of the soil acidity oralkalinity of a soil.
l Measures the negative logarithm ofthe hydrogen ion activity of the soilsolution.
Soil acidity
Is caused by many factors such as
l Excessive rain which leaches basiccations (Ca, Mg, K)
l Use of nitrogenous fertilizer like urea,ammonium sulphate etc.
l Oxidation of iron pyrite containingminerals.
Correction of soil acidity
l Soil acidity is corrected by liming;soils which have a pH value of lessthan 5.5 could be limed.
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Salinity and alkalinity
l Occurs in arid and semi arid regions,where precipitation is insufficient tomeet evapotransporation needs ofplants, when salts move up to thesurface.
l Salt affected soils occur withinirrigated lands.
l Salts are added through irrigationwater; through over-irrigation andsalts accumulate in poorly drainedareas.
l Salt content in soils is measured interms of electrical conductivity (EC).
l A saline soil has a pH of less than8.5, but soils are well flocculated.The EC is more than 4 deci Seimensper meter (4dS m-1.)
l Soils which are saline causeproblems to crops during dry weather.Loss of crop yield from poor growthis common.
l Alkaline soils have high pH and ahigh concentration of sodium in them.
l Alkaline soils are deflocculated,drainage is poor and growing plantsis difficult due to high pH and highercontent of sodium in the soil.
l Draining, flushing after ploughing andaddition of organic matter andgypsum could correct theseproblems.
Cation exchange capacity(CEC)
l The power to retain cations at thesurface of soil colloids is referred toas the cation exchange capacity.
l Soil colloids of clay and organicmatter have this property due to thepresence of negative charges at thesurface.
l CEC is defined as the sum of cationsheld by a kilogram of soil. It isexpressed in Cmol/Kg soil.
l Clays like kaolinite have low CECand the CEC is pH dependent.Organic matter has a large CEC butit too is pH dependent.
l Montmorillinitic clay has high CECdue to the negative chargesdeveloped through loss of cationsduring formation of these clays.
l Practices like fertilization, liming,irrigation and addition of organicmanures can increase theexchangeable cations.
Soil organic matter (SOM)
l Consists of living organisms, deadplant and animal residues.
l Is the most chemically active portionof the soil.
l Is a reservoir for various essentialelements.
l Contributes to CEC.
l Promotes good soil structure.
l Buffers soil pH.
l Promotes good air and waterrelations in plants.
Humus :
Is the portion of the organic materialthat has been transformed into arelatively stable form by soilmicroorganisms. (organic colloids).
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Functions of organic matterin soil
l Supplies N, P and S to plant growth.
l Increases CEC in a soil.
l Have large surface area and hashigh CEC.
l Holds up to twenty times their weightof water.
l Holds cations and anions andreleases them slowly.
l The ratio of C:N:P:S is 10: 1: 0.5 : 0.1
l Effects the breakdown of pesticidesand weedicides.
l Chelates micronutrients such as Zn,Mn and Cu making them moreavailable to plant roots.
l Buffers extreme acidity, salinity andalkalinity.
Fate of organic material addedto soils
l Undergoes decomposition (only bio-degradable materials) through soilmacro and micro fauna and flora.
l Final degradation is made by soilmicroorganisms.
l The final product is a humus typematerial which has a C: N ratioaround 9:1- 12:1.
l All complex carbon products areconverted into simple compounds.
The nitrogen cycle
This is one of the most important naturallyoccurring events. It is discussed under
l Nitrogen fixation.
l Conversion of N in soil.
l Plant and microbial uptake of solubleN compounds.
l Agronomic circulation and removalof N.
Nitrogen fixation
l Nitrogen is a very inert gas whichconstitutes 78% of the atmosphericair; it has low chemical reactivity.
l For use by plants it has to beconverted to ammonium (NH
4
+) ornitrate (NO
3-)
l Only a few microorganisms canutilize N gas which is referred to asN fixation.
l Fixation is effected by microbialaction, industrial synthesis and highthermal combustion and lightning.
Conversion of N in soil
Forms of N occuring in soils
l Soluble mineral forms, ammonium,nitrate, nitrous oxide (gas)
l Soluble organic compounds, urea,aminoacids.
l Living organisms, plant roots, fungi,bacteria, soil animals.
l Insoluble forms, organic nitrogen,ammonia bonded to clay.
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Transformation between the different formsis mediated by soil microorganisms.
Mineralization
l Conversion of N in organic residuesand soil organic N into soluble formsthrough mineralization.
l Carbon sources are degradedsources of energy.
l N in excess of microbial need isliberated.
l The following sequence of reactionstakes place.
i. Ammonification: Complex proteincompounds are broken down toammonium compounds bymicroorganisms.
ii. Nitrification: A m m o n i u mcompounds are oxidized to nitrite andto nitrate by two specific types ofsoil bacteria, Nitrosomonas andNitrobactor.
iii. Denitrification: The nitrates arereduced to nitrogen gas under poorlyaerated conditions through specificmicroorganisms.
Other cycles found in nature
l Carbon cycle
l Sulphur cycle
l Phosphorus cycle
Assignment1. Look for physical characteristics of a soil in your area.
(Note: e.g. Texture by feel, colour visually, drainage by soil colour)
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Section II
SOIL FORMATION
WEATHERING OF ROCKS ANDSOIL FORMATION
Introduction
Rock weathering and soil formation takesplace at the same time. Rocks disintegrateand decompose under natural conditionsto give rise to parent material on whichsoils develop. The soil which form out ofthe parent material has no resemblance tothe latter.
Weathering refers to the chemical andphysical disintegration and decompositionof rocks that take place due to the mineralscontained in them being not in equilibriumunder the temperature, pressure andmoisture conditions of the atmosphere -lithosphere interphase.
Rocks contain a single or a number ofdifferent minerals. Minerals are chemicalsubstances that are either simpleelements like graphite or contain a numberof elements forming complex compounds.
ROCK WEATHERING
Physical Weathering
Disintegration and decomposition of rocksresult in the formation of new chemicalcompounds. Disintegration takes place dueto physical changes brought out by externalelements of:
l Temperature changes
l Moving water
l Frost
l Moving ice
l Wave action
l Wind
l Plant roots
Temperature changes
The expansion and contraction due totemperature changes of hot and coldnessresults in cracking of rocks.
Moving water
Can carry large boulders, that crack andbreak in their path.
Frost
Freezing of water results in increase involume. Water entering cracks and crevicesof rocks expands resulting in cracking ofrocks.
Moving ice
Can disintegrate rocks.
Wave action
Carry sand which abraises and cuts thesurface of rocks.
Hot wind
Blowing over deserts carries sand, whichabraises rocks and breaks them.
Plant roots
Enter crevices in rocks and with growthexert pressure to widen cracks.
Physical weathering does not alter thechemical composition of the rocks.
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Geochemical Weathering
Takes place in the C horizon; the weatheringreactions that take place are oxidation,reduction, combinations of both in alternatecycles, hydration, solution and hydrolysis.
Oxidation
Occurs in well-aerated rocks. The mostimportant specific reaction is that of ferrousto ferric ion.
Fe2+ Fe3+ + e*
* e = electron transfer
Reduction
Takes place in environments where thematerial is water saturated, oxygen supplyis low and biological demand for oxygen ishigh; e.g. Ferric ion is converted to ferrousform. If the ferrous ion persists in the systemit reacts to form sulphides and relatedcompounds which impart a green and bluegreen colour to the soil.
Oxidation – Reduction
Fluctuations from oxidizing to reducingconditions in response to variations inweather throughout the year. Under theseconditions, ferrous and manganese ionsremain stable even in the oxidized state.
Hydration
Refers to the association of water moleculesor hydroxyl groups with minerals, oftenwithout actual decomposition ormodification of the mineral itself. Forexample, Anhydrite is converted to gypsum.
CaSO4 + 2H
2O CaSO
4.. 2H
2O
Hydrolysis
Is the attack of highly charged hydrogenion on the crystal structure of minerals. Forexample, Feldspar is converted to silicicacid and potassium is released. Hydrolysisresults in complete disintegration or drasticmodification of weatherable primaryminerals.
Factors involved in soilformation
l Parent material
l Relief / Topography
l Climate
l Organisms
l Time
Parent material
Is defined as the state of the soil systemat time zero of soil formation. In general,younger the soil the greater the influenceof, and relationship of, soil properties to thesoil parent material.
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Relief / Topography
Within specific geographic regions thefollowing soil properties are found to berelief related.
l Depth of soil profile
l Thickness and organic mattercontent of a horizon
l Relative wetness of profile
l Colour of profile
l Degree of horizon differentiation
l Soil reaction (pH)
l Soluble salt content
l Kind and degree of pan development
l Temperature
Climate
Exhibits its influence on soil formation bycontrol of the chemical and physicalreactions taking place in the soil and by itscontrol over organic matter content andthrough erosion and deposition of soilmaterials. Rain water dissolves solublematerials, promotes vegetation andcontributes to organic material and isinvolved in transport of materials.
Following changes are brought by rain.
l Soil pH decreases.
l N content increases with increasedrainfall.
l Clay content increases withincreased rainfall.
l Carbonate content decreases withincreased rainfall.
Fig. 2. Landscape and soil profile ofRed Yellow Podzolic Soils (Galigamuwa)Photo : Soil Science Society of Sri Lanka
Temperature
With increase in temperature soil colourbecomes more reddish, N content and soilorganic matter content decreases, and claycontent increases.
Organisms
Organic material found in the A horizon areacquired through the passage of materialpassing through the alimentary tracts ofinsect larvae, worms and associated soilfauna. Voids are caused by borrowinginsects and worms. Channels are made byroots and rhizomes of plants.
Time
Young, immature and mature soils aredescribed to relate their properties to time.Young soils have more weatherableminerals and senile soils have moresesquioxides of heavy minerals.
The Soil Profile
Ap 0-12/15 cm
BA 12/15-20/33 cm
B†120/33-85 cm
B†2 85-120 /145+cm145+cm145+cm145+cm145+cm
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A complete soil profile is a vertical exposureof a surfacial portion of the earth’s crustthat includes all the layers that have beenpedogenically altered during the period ofsoil formation and also the deep layers thatinfluenced pedogenesis. A soil profile maybe observed in a freshly dug pit, along aroad bank, etc. (Fig. 2)
Soil Horizon
Is a layer of soil approximately parallel tothe soil surface, with characteristicsproduced by soil forming processes. (Fig.3) In the field morphological characters ofcolour, texture, consistency, structure,cutans, nodules or concretions, voids, andboundary characters are used indistinguishing horizon differences.
Fig. 3. Soil profile of Reddish BrownEarths in the Anuradhapura districtDiagramatic representation
Source: C.R.Panabokke
A-horizon}
}B-horizon
C-horizon
}Quartzgravellayer }
Master horizon designations
i. Organic horizons on mineral soilsurfaces
Designation O – Organic horizonsformed or forming above the mineralpart, dominated by fresh or partiallydecomposed organic materials.
ii. Mineral Horizons
A : This horizon has organic matteraccumulation adjacent to the surface,horizons that have lost clay, ironand aluminium with resultantconcentration of quartz or otherresistant minerals of sand or silt size.
Sub division of A
Al : Mineral horizons formed at thesurface where humified organicmatter is associated in the mineralfraction. Dark or dark gray in colour.
A2 : Mineral horizon where clay, iron andaluminium are lost and quartz occur.
A3 : A transitional horizon between A andB, with characters of overlying A1 orA2, but also have some charactersof B.
AB : A transitional horizon between A andB having an upper part dominatedby properties of A and a lower partby B but the two parts cannot beeasily separated.
AC : A transitional horizon between A andC having subordinate properties ofboth A and C but not dominated byeither characters of A or C.
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B Horizon: The dominant featuresare :
i. Accumulation of illuvial clay, iron andaluminium sesquioxides and humus.
ii. Coating of the sequioxides by darkeror stronger colours
Sub division B
B1 : A transitional horizon between B andA1 or between B and A2 in which thehorizon is dominated by propertiesof overlying A1 or A2.
B2 : A transitional horizon without clearlyexpressed subordinate characteris-tics.
C Horizon : Is a mineral horizonexcluding bed rock, that is either likeor unlike material on which the soilformed.
R Horizon : It is presumed to be likethe parent rock from which theadjacent overlying layer or horizonhas formed.
Assignment1. Observe a soil profile in your area and try to demarcate various horizons
(Note : Freshly cut pit or road bank could be used)
Table 1: Comparison of soil horizon nomenclatures of 1962 and 1981
Old (1962) New (1981)
A Horizon O O- Ap (Cultivated soils)A1 A / ApA2 EA3 AB / EBAC AC
B Horizon B BB1 Btl /BwB2 BC / CB Bt3
C Horizon C CR Horizon R R
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Section III
SOILS OF SRI LANKA
SOILS OF SRI LANKA ANDTHEIR FERTILITYCHARACTERISTICS
i. Sri Lanka has a wide diversity of soiltypes. This diversity is chiefly due toclimate and topographic factors.
ii. The mean annual rainfall varies from1250 – 5000 mm in the south westernquarter of the island to less than1250 mm in the northwest andsoutheastern parts of the country.
iii. Based on the rainfall patterns, threegeographic zones, dry, wet andintermediate zones have beenidentified.
iv. The topographical boundaries arelow country 0 – 300m, mid country,300-900m and the upcountry> 900m.
v. The parent material of most soilshas been dislocated and isconsidered to be colluvial andcolluvial residuum.
Soil classificationClassification of soils based onmorphological and other charactersbegan with the work of Dokuchaevetal in the 19th century. The mostaccepted types of classification arethose developed by of the UnitedStates Department of Agriculture(USDA) (Soil Taxonomy) and theFAO-UNESCO. The former is useddue to its simplicity.
In the USDA system there are 11orders and a large number of sub-orders, great groups, sub-groups,series and families. In this discussionclassification is confined to orders,suborders and great groups, only.
Soils of the Dry and Semi- Dry Intermediate Zones.
Older name of great New name (USDA) of great
group group
Reddish Brown Earths Rhodustalfs
Low Humic Gley soils Tropaqualfs
Non-calcic Brown soils Haplustalfs
Red Yellow Latosols Haplustox
Alluvial soils Tropaquents and Tropofluvents
Solodized Solenetz Natraqualfs
Sandy Regosols Quartzipsamments
Grumusols Pellusterts
Immature Brown Loams Ustropepts
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Fertility characteristics of dryzone soils
(See Soil Map of Sri Lanka Fig. 4)
a. Reddish Brown Earths(RBE)
These soils are confined to the dryzone and occur in a catenarysequence, occupy the crest, the well-drained upper and mid slopes of theundulating landscapes. The colourof the surface is reddish brown whendry, turns to dark reddish brown whenmoist. A subsoil horizon with a highpropotion of quartz gravel is present,the depth to the gravel layer isvariable. Soils are extremely hardwhen dry, friable to firm when moist.Soil reaction is slightly acid to neutral.Base saturation is 60-80% . Soilsare low in P but are reasonably highin K. They have a low water holdingcapacity with a rapid release of soilmoisture at low tensions. The organiccarbon content of the soils is low,1-2% .
b. Non-Calcic Brown soils(NCB)
Occur in most parts of NorthKurunegala, Anuradhapura, EastPolonnaruwa and East Moneragalaand Batticaloa Districts. Colour ofthe surface soil is dark brown to darkgreyish to red yellowish brown. Thesesoils are shallow. The surface layersare sandy loams and the waterholding capacity is low with rapid
infiltration. During rain upwelling ofwater is frequent. Soil reaction ismedium acid. These soils are poorin organic carbon and P content.Base saturation is 50-70% with high% of Ca 2+ in the bases. They areeasily workable than the ReddishBrown Earths.
c. Low Humic Gley soils(LHG)
They are developed from colluvialdeposits on the foot slopes ofundulating landscapes. They arecharacterized by wetness or gleyingthroughout the profile. Soils areextremely hard when dry and stickywhen wet, drainage is poor and basesaturation of subsoil is 90-100%, soilreaction is moderately alkaline . Theyhave a high CEC and are moresuitable for rice but other crops canbe grown with proper drainage.
d. Red-Yellow Latosols(RYL)
Occur in the North Western parts ofthe Puttalam and Jaffna peninsulaand in few locations in the northernand south eastern parts of thecountry. These soils are deep withno clear horizon boundaries. Thephysical properties of these soils aregood. Base saturation is 20-60% andsoil reaction is medium acid. Theyhave rapid infiltration and low waterholding capacities. They are very lowin plant nutrients as very littleweatherable materials are found.
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Fig. 4: Soil Map of Sri Lanka
Source: NRMC, Department of Agriculture
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e. Alluvial soils (AL)
Are found on flat flood plains. Thepoorly drained alluvium shows agreyish colour; better-drained soilsare brownish to yellowish brown. Soilreaction is slightly acidic to slightlyalkaline. Base saturation is 60-90%.They have more organic carbon, Pand K than RBE soils. Poorly drainedsoils are suitable for rice but in well-drained soils many arable crops canbe grown.
f. Solodized -Solenetz (SS)
Their occurrence is related to thepresence of sodium salts in theparent material. These soils have acolumnar structured B horizon. Theyoccur on estuaries and in inlandvalleys of the Mahaweli system B inthe Kandakadu – Tirikonamadu area.These soils are poorly drained andare generally not suitable forprofitable cropping, except withamendments.
g. Regosols (R)
They are sandy and are found alongor near the coast line. Regosolsfound in areas of Kalpitiya, Nilavellyand South of Batticaloa district, haveweakly humiferous horizonsoverlying yellowish or brown sand.Texture is fine sand to coarse sand.Infiltration is rapid ; underneath thesandy layer a film of fresh water often
floats over saline water due todifference in densities. This enablesgrowth of deep-rooted plants andirrigation of shallow-rooted crops.Soils are very low in soil organicmatter content and plant nutrients.Generally, crops can be grown withhigh management.
h. Grumusols (G)
These soils are formed fromtransported material mainly of alluvialnature. They are found in pockets ofMurunkan, Hettipola (Matale District)and Ambewila ( Ratnapura District).Soils are black to very dark graybrown with a higher percentage ofclay. The clay is of the expandingtype and cracks during dry seasons.A low amount, of gilgai is formed dueto shrink and shrivel characters.These soils have a high CEC andare very productive. Drainage is poorand soil reaction is neutral.
i. Immature Brown Loams (IBL)
Found along the western borders ofthe Ampara and north easternborders of the Badulla District. Soilsare relatively infertile, shallow andneed good management for cropproduction. The soil reaction isslightly acid to neutral. They arerelatively young soils.
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Fertility characteristis of the wet zone andsemi-wet intermediate zone soils
a. Red – Yellow Podzolicsoils (RYP)
Are found both in the lowlands andcentral highlands. They occur indiverse land forms that are foundmostly in the hilly parts of the country.Certain geomorphic variations havegiven rise to the modal groups.
a (i). Sub group with astrongly mottledsubsoil
This group of soils is found in the semi-wetintermediate lowlands of the Kurunegaladistrict. The colour of the surface soil isdark brown to reddish brown. Surface soils
have loamy to sandy loam texture andsubsoils are sandy clay loam to sandy clay.These soils are acidic in reaction; have lowbase saturation and low CEC. During dryweather the subsoil becomes very hardand limits root movement. Requires additionof organic materials for good management.
a (ii). Subgroup with soft orhard laterite
These soils have hard laterite formed atdepths of 125 – 250 cm. The ‘Cabook’which is soft laterite becomes irreversiblyhard upon drying. They are found in theuplands of the Colombo, Gampaha andKalutara district on the foot slopes. Thebase saturation is 15-30% and CEC is verylow. Requires good management to growcrops.
Soils of the Wet Zone and Semi-Wet Intermediate Zone of Sri Lanka
Older name New name (USDA)Red-Yellow Podzolic soils Rhodudults/ TropudultsThe Modal group
Sub group with strongly mottled subsoil TropudultsSub group with soft or hard laterite PlinthudultsSub group with prominent A1 horizon TropohumultsSub group with semi-prominent A1 horizon TropudultsSub group with dark B horizon Humudults
Reddish Brown Latosolic soils Rhodudults/TropudultsImmature Brown Loams Eutropepts/DystropeptsBog soils/ Half Bog Soils Tropohemists/TroposapristsLatosols and Regosols. Quartzipsamments(on old red and yellow sands)
24
a (iii). Sub-group withprominent A - horizon
These soils are found under wet grasslands(pasture) of the Nuwara Eliya district atelevations around 2000 m. These soils havelow base saturation (5-10%). Soils havehigh organic matter (5-15%). Soils arestrongly acidic and need liming beforegrowing crops.
b. Reddish Brown Latosolicsoils (RBL)
These soils are found in the Kandy,Galagedara, Mawanella and Middeniyaareas. They have excellent physicalproperties. They are deep soils resistant toerosion. Base saturation is 25-35%. Soilsare medium acid and have high waterholding capacity. These are some of themost fertile soils found in the area.
c. Immature Brown Loams (IBL)
These are found in the Kandy, Matale andMawanella regions. They have low basesaturation and low CEC. The soil reactionis acidic.
d. Bog and half-bog soils(BHB)
They are found in the low-lying areas of theColombo, Kalutara, Galle, Matara andRatnapura districts. They are ill-drained.Bog soils have over 30% organic matterwhile half bog-soils have lesser amounts oforganic matter. These soils are stronglyacidic. The CEC is high but base saturationis low. Because of their poor structure andlow bulk density, the management of thesesoils is difficult.
e. Latosols and Regosols onold red and yellow sands
These are found in the Madampe –Negombo areas. They have low claycontent, low base saturaion and highamount of free sand. They have poor waterholding capacity and needs goodmanagement for growing crops. The soilreaction is acidic and organic matter contentis very low.
Assignments1. Find out the major soil groups in your district by referring to the soil map.
By observing the soil profile and soil, make comparisons given inliterature and your own observations.
2. List major crops grown in your area, both annuals and perennials.
25
Section IV
PLANT NUTRIENTS
Introduction
The success of farming depends largely onthe growth of crops. Crop growth isinfluenced by a number of factors of whichplant nutrients are an important group.There are 16 nutrient elements consideredessential for plant growth.
An essential plant nutrientelement has the followingcharacteristics
i. The completion of the life cycle ofthe plant cannot be achieved in theabsence of such an element.
ii. Plays a specific role in the plant.
iii. Causes set back to growth of theplant showing visual symptoms whenthe plant is deficient in it.
Essential elements are inorganic in natureand they are grouped into
i. Primary nutrients – Required in largerquantities
ii. Secondary nutrients – Needed inlesser amounts than primarynutrients
iii. Micronutrients – Required in smallquantities
These sixteen elements are listed inTable 2. Carbon, hydrogen and oxygenare obtained from air & water. The other
thirteen elements are referred to as fertilizerelements and have to be obtained from thesoil. Their addition in quantities necessaryfor plant growth will increase the growthrate, dry matter content and yield of thecrop.
l Plant nutrients are usually absorbedthrough roots. Roots have the abilityto absorb nutrients selectively.
l Root absorption takes place both asactive and passive absorption.
Active absorption takes placeas an exchange phenomenonand requires energy. Mostplant nutrients are absorbedin this manner.
Passive absorption is part ofthe transpiration cycle (massflow). Water and somedissolved solutes areabsorbed by this process.
l Gas exchange takes place throughthe stomata found in leaves. Carbondioxide required for photosynthesisand oxygen required for plantrespiration are exchanged throughthe leaves.
The supply of an adequate quantity of aparticular nutrient for crop growth dependson both the behaviour of that nutrient in thesoil and the ability of the crop root systemto utilize it.
When these elements are not available tothe plant in quantities optimum for growth,the quantity and quality of yield is affected.
26
Deficiency of an element
When an essential element is at a lowconcentration in the plant tissues it will resultin the decrease in normal growth of theplant, affect the crop yield and producemore or less distinct deficiency symptoms.
l Typical deficiency symptoms are notoften clearly defined. Masking effectsdue to other nutrients, secondarycauses like disease, herbicidetoxicity or insect infestation canconfuse field diagnosis.
Nutrient Chemical symbol Form taken up by plant
Primary Nutrients
1. Carbon C CO2, HCO
3-
2. Hydrogen H H2O
3. Oxygen O H2O, O
2
4. Nitrogen N NH4+, NO
3-
5. Phosphorus P H2PO
4-, HPO
4-2
6. Potassium K K+
Secondary Nutrients
7. Calcium Ca Ca 2+
8. Magnesium Mg Mg2+
9. Sulphur S SO42-
Micro Nutrients
10. Iron Fe Fe2+, Fe3+, chelate
11. Zinc Zn Zn2+, Zn(OH)20, chelate
12. Manganese Mn Mn2+, chelate
13. Copper Cu Cu2+,chelate
14. Boron B B(OH)30
15. Molybdenum Mo MoO4-
16. Chlorine Cl Cl-
Table 2. NUTRIENTS ESSENTIAL FOR PLANT GROWTH AND FORMS INWHICH NUTRIENTS ARE TAKEN UP BY PLANTS
l Waterlogged conditions or dry soilsand mechanical damage can oftencreate symptoms that mimicdeficiencies.
l Deficiency symptoms always indicatesevere starvation.
Insufficient levels
When the level of an essential plant nutrientis below the required amount for optimumyields or when there is an imbalance withother nutrients it is considered insufficient.
27
The symptoms of this condition are seldomclearly visible, resulting in poor yield.
Toxicity
Certain essential plant nutrients, if takenup in excess will often cause nutrientimbalances and will result in poor plantgrowth, delayed maturity, stunted andspindly growth and also show visiblesymptoms of chlorosis or necrosis.
Hidden hunger
There are no visual symptoms of deficiencybut the plant is not producing at its capacity.When the plant reaches the level wheresymptoms appear the yield may alreadyhave been greatly reduced.
Identification of nutrient hunger signs isbasic to profitable crop production.Deficiency symptoms can be categorizedinto five types.
1. Chlorosis, which is yellowing, eitheruniform or interveinal of plant leaftissue due to reduction in thechlorophyll formation.
2. Necrosis, or death of plant tissue.
3. Lack of new growth or terminalgrowth resulting in rosetting.
4. An accumulation of anthocyanin and/ or appearance of a reddish colour.
5. Stunting or reduced growth witheither normal or dark green colour oryellowing.
The following simple key (Table 3) gives aplace to start diagnosing nutrientdeficiencies.
28
Table 3. KEYS TO NUTRIENT DEFICIENCY SYMPTOMS IN CROPS
NUTRIENT COLOUR CHANGE IN LOWER LEAVES
N Plant light green, older leaves yellow
P Plants dark green with purple cast, leaves and plants small
K Yellowing and scorching along the margin of older leaves
Mg Older leaves have yellow discolouration between veins-finallyreddish purple from edge inward
Zn Pronounced interveinal chlorosis and bronzing of leaves
NUTRIENT COLOUR CHANGE IN UPPER LEAVES
(Terminal bud dies)
Ca Delay in emergence of primary leaves, terminal buds deteriorate
B Leaves near growing point turn yellow, growth buds appear aswhite or light brown, with dead tissue.
NUTRIENT COLOUR CHANGE IN UPPER LEAVES
(Terminal bud remains alive)
S Leaves including veins turn pale green to yellow, first appearance inyoung leaves.
Fe Leaves yellow to almost white, interveinal chlorosis at leaf tip
Mn Leaves yellowish-gray or reddish, gray with green veins
Cu Young leaves uniformly pale yellow. May wilt or wither withoutchlorosis
Mo Wilting of upper leaves, then chlorosis
Cl Young leaves wilt and die along margin
Assignments1. Observe any deficiency symptoms shown in crops grown in your area.
Symptoms given above could be a guideline for your study.
2. Look out for iron toxicity in paddy especially in wet zone areas.
29
Fig. 5. Nitrogen deficiency in rice
Fig. 6. Rice plants with and without nitrogen
Note: See Appendix 1 &1a for nutrient deficiencies and toxicities of other elements.
Source: IRRI
30
FATE OF NUTRIENTELEMENTS IN SOIL
l Nutrients are lost through
Crop removal
Erosion
Leaching
Volatilization
Denitrification
Fixation
Crop removal
l Plant species have specificrequirements of plant nutrients.
l Nutrient removal depends on
Growth condition
Crop sanitation
Cultivation
Yield obtained
l Grain crops require more nitrogenthan other nutrients. Pulses requiremore phosphorous while crops suchas tomato, banana and pineapplerequire more potassium comparedto other nutrients.
Erosion
l Entire top soil is lost through erosionby water; this results in loss of soilphosphorus.
Leaching
l Water percolating through a soilprofile carry dissolved nutrientelements. Nutrients are easily lostin humid regions and sandy soils.
l Bare soil loses more nutrients thancultivated soils.
Volatilization
l Nitrogen is easily lost throughvolatilization as ammonia, particularlyin paddy soils and upland soils withpoorly drained areas. This is referredto as ammonia volatilization. Thisloss is enhanced by high temperatureand wind.
Denitrification
l Nitrate form of N is lost throughdenitrification where nitrogen gas ornitrous oxide is released. This lossoccurs mainly in paddy soils and inupland soils which are saturated withwater periodically or part of the time.
Fixation
l Takes place by conversion of anutrient to an unavailable form.
l Phosphorus is converted tounavailable forms both in acidic andalkaline soils.
l Potassium and ammonium N can befixed by certain clay minerals.
CHEMICAL FERTILIZERS
l Fertilizers are substances intendedfor improving the nutrition of plants.
l Promote growth by increasing plantmass and yield.
l Increase the harvested mass suchas leaves, fruits and grain.
l Improve quality, market quality, valueand nutritional quality.
Note: See Appendix 2 for FertilizerStandards
31
NITROGEN NUTRITION ANDFERTILIZERS
Function in plants
l Makes up 1-4% of the dry weight ofplants.
l Taken up from the soil in the form ofnitrate (NO
3-) and ammonium (NH
4+).
l Combines with carbohydratemetabolism to form aminoacids andproteins.
l Essential constituent of protein,chlorophyll etc.
l Assimilation in plant depends on typeof plant, stage of maturity and supplyin the soil.
Sources of N to plants
l Free living microorganisms fix16-50 kg N/ha/year
l Organic matter in soil bydecomposition produce 1-2% of N peryear and contribute to 20-45 kg N/ha.
l About 6 kg N/ha/year are brought byrainwater.
Nitrogen fertilizers
Urea
l Ammonia is made by compressinghydrogen and air at high temperatureusing a catalyst.
l Is manufactured by combiningammonia and carbon dioxide gasunder high pressure.
l Is a white crystalline organiccompound containing 40-48% N.
l The pelletted form containing 46% Nis used as a fertilizer.
l Is soluble in water.l Used both as a soil and foliar
applicant.l Contains an impurity of biuret, which
is formed during the prilling process.l Biuret in excess quantities is harmful
to plants.l Use of urea having less than 1%
biuret is allowed by Sri Lankastandard.
l Urea is hygroscopic. When mixedwith triple super phosphate, it tendsto lose its granular form due tohydration.
l Urea on addition to soil is convertedto ammonium carbonate and tonitrate by enzymatic reaction andmicrobial action.
l Addition of urea to uplands results inacidification of soils.
Ammonium sulphate
l Contains 21% N and 24% S
l Is light grey or white in colour
l Is soluble in water
l In upland soils it is converted tonitrate
PHOSPHORUS NUTRITION ANDFERTILIZERS
Functions in plants
l Makes up 0.1-0.4% of the dry matterin plants.
l Involves in carbohydrate breakdownfor energy release, cell division andtransfer of inherited characters.
l Stimulates early root growth anddevelopment.
l Hastens maturity of plant
32
l Improves fruit and seed production
l Involves in energy transformation.
Plant uptake is governed by
l Type of plant.
l Stage of plant maturity.
l Competition between plant roots andsoil chemicals for phosphorus in soiland fertilizer.
l Absorbed in the H2 PO
4- and H PO
42-
forms.
Phosphorus fertilizers
l P in fertilizers is expressed as P2 0
5.
l The calculation is P2 O
5 content = P
content x 2.29 or P2O
5 content x 0.44
= P content.
Rock phosphate (RP)
Both imported rock phosphate containinghigh citric acid soluble P (28% total P
2O
5)
and local Eppawala rock phosphate of lowcitric acid soluble P (30% total P
2O
5) are
marketed in Sri Lanka. Rock Phosphate isspecially recommended for perennial cropsgrown in the acid soils of the wet zone. Thismaterial gets slowly solubilized in soils withlower pH values. Eppawala rock phosphate(ERP) is not recommended for annual cropsbut is recommended for tree crops grownin acidic soils.
Triple superphosphate (TSP)
Contains 45-50% P2 O
5. According to Sri
Lanka standards it should contain 46%P
2 O
5, 12 – 16% Ca and 1-2 % S. Most of
the P is in water soluble forms; it isrecommended for all food crops.
Diammonium phosphate (DAP)
l Contains both N (18%) and P (46%P
2 O
5) and is water soluble.
POTASSIUM NUTRITION ANDFERTILIZERS
Function in plants
l Regulates cell water balance.
l Stimulates enzyme activity.
l Used in storage and release ofenergy.
l Influences processes of cell division,formation of carbohydrate,translocation of sugars and synthesisof proteins.
Forms of K in soils
Based on the degree of availability.
l Difficultly available 90-98%.
l Slowly available 2-10%.
l Readily available 1%, easilyabsorbed by plants.
l Equilibrium exists between the three.
Potassium requirement ofplants
l Seeds contain 0.1 – 1.0%.
l Makes up 1-4% of the dry matter ofplants.
l Absorbed as K+.
Potassium fertilizers
l K is expressed as K2O in the fertilizer
trade.
l K x 1.23 =K2O and K
2O x 0.83 = K.
33
Muriate of potash(Potassium chloride)
l Contains 48-62.5% K2O.
l Sri Lanka standard stipulates 60%K
2O.
l Is pinkish red or white in colour.
l Water soluble.
l Not suitable for crops like tobacco aspresence of chloride leads to poorburning quality.
Sulphate of potash (Potassiumsulphate)
l Contains 50% K2O, 16% S and not
more than 2% Cl.
l Water soluble.
Magnesium Nutrition andFertilizers
Function in plants
l Metallic element of chlorophyll. Playsan important role in photosynthesis.
Deficiency symptomsl Frequent on acid coarse-textured
soils, under high annual rainfall.
l Occurs in soils with high Ca or K.
Magnesium fertilizers
Dolomite limestone (12%Mg); Insoluble inwater.
Magnesium sulphate
l Kieserite MgSO4.7H
2O (18%Mg);
Partly soluble in water.
l Epsom salt MgSO4.7H
2O (10%Mg);
water soluble.
Synthetic chelate – Mg EDTA
l Rates of Mg recommendation varywith crop, degree of deficiency andsource.
Calcium Nutrition andFertilizers
Function in plants
l Cell walls are built up of calciumcontaining substances.
Deficiency symptoms
l Yellowing of young leaves.l Failure of new leaves to emerge.l Empty groundnut shells.l Blossom end rot in tomato and other
fruits of chilli, brinjal etc.l Deficiency occurs in acid sandy soils.
Calcium fertilizersl Calcium is found in limestone,
dolomite, TSP and gypsum.
l Gypsum contain 23% Ca. and is asource of sulphur too.
Sulphur Nutrition andFertilizers
Function in plants
l Sulphur is an essential element ofproteins, found in sulphur containingamino acids such as cysteine andmethionine.
l Involves in the metabolic activities ofvitamin B.
l Facilitates the stabilization of proteinstructure.
l Total S content in plant tissues is 0.2to 0.5%
34
Deficiency symptomsl Youngest leaves turn uniformly
yellowish green or chlorotic due toinhibition of protein synthesis.
l Restricted shoot growth, unevenflower production.
l Short stunted plant, thin and woody.
Sulphur containing fertilizersl Ammonium sulphate - 24% Sl Gypsum (ordinary) - 16% Sl Single (ordinary)
superphosphate(SSP or OSP) - 12%S
Micronutrients, their role inplant nutrition andmicronutrient fertilizers
Availability to plants
l Availability depends on soil pH.Boron, copper, iron, manganese andzinc availability decreases withincrease in pH from 5-7.
l Availability of molybdenum increaseswith increase of pH.
l Mineral soils with substantial organicmatter can have adequatemicronutrients.
l High organic matter containing soilsrequire addition of copper andmanganese.
l Plant analysis should be done toconfirm micronutrient deficiencies.
Specific elements and theirnutrition
Boron (B)
l Boron deficiency occurs in coarse-textured soils in the wet zone.
l Boron deficiency occurs withdecrease in soil moisture.
l Boron is involved in cell division, fruitformation, carbohydrate and watermetabolism, protein synthesis, andseed development in plants.
l Translocation within plants do notoccur. A constant supply isnecessary throughout the growingseason.
l Application rates vary from 0.1 to 3kg/ha.
l Range between boron deficiency andtoxicity is very narrow. Overapplication can result in crop failure.
Boron fertilizer
l Borax 11% B.
l Sodium tetraborate 14% B.
Copper (Cu)
l Sandy soils contain low amounts ofcopper. Copper content increaseswith clay content of soil.
l Available copper content increaseswith organic matter in mineral soils.
l Deficiency occurs in high organicsoils, acid sandy soils and incalcareous soils.
l Copper has a role in enzymesystems.
l Deficiency symptoms are die-backof twigs and yellow leaves in citrus,die back of leaves in vegetables andtip-burn in cereals.
l Copper has a residual crop response.Over application results in toxicity.
35
Copper fertilizers
l Copper sulphateCu SO
4. 5H
20 25% Cu.
l Copper chlorideCuCl2 17% Cu.
l Synthetic chelatesCu EDTA 9% Cu.
Iron (Fe)l Iron is involved in respiratory
reactions and enzymatic reactions.l Availability of iron decreases with the
increase of soil pH. Soils which arepoorly drained and with freecarbonates are deficient in Fe.
l Too much liming results in irondeficiency (lime-induced chlorosis)
l Iron deficiency appears as yellowingof the interveinal regions of leaves.
l Severe deficiency results in chlorosisand the leaves turn white andeventual leaf loss.
l Iron toxicity occurs in low pH soilsl Iron deficiency is corrected by foliar
application.l Iron fertilizers applied to soil are
ineffective as they are converted tounavailable forms.
Iron fertilizers
l Ferrous sulphate 20%. Fe.
l Iron chelates Fe EDTA 7% Fe.
Manganese (Mn)l Availability of Mn is related to soil
pH, organic matter content anddegree of aeration.
l Deficiency occurs in alkaline soils,sandy soils and organic soils.
l Toxicity results in acid soils.
l Manganese is involved in enzymesystems related to chlorophyllproduction, metabolism ofcarbohydrates and N.
l Deficiency symptoms appear asinterveinal chlorosis (could beconfused with Fe or Zn deficiency).In severe cases there is chlorosis,leaves turn brown and leaves die.
l Basal application of fertilizer Mn issuitable to correct deficiency. LikeFe, foliar application is the best.
Manganese fertilizers
l Manganese sulphate 23 -28 % Mn.
l Synthetic chelates Mn EDTA 5-12%Mn.
Molybdenum
l Molybdenum availability is low in acidsoils. Liming can correct deficiency.
l Molybdenum involved in N fixationin legumes. These crops requirehigher rates.
l Molybdenum deficiency is commonin cauliflower causing leaf marginalscorching.
Molybdenum fertilizers
l Ammonium molybdate 54% Mo.
l Sodium molybdate 39% Mo.
Zincl Availability to plants decreases with
increasing soil pH. Coarse-texturedsoils and low organic mattercontaining wet soils are marginal inzinc.
36
pH 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0
Molybdenum
Iron
Zinc
Copper
Boron
Magnesium
Calcium
Sulphur
Potassium
Phosphorus
Nitrogen
Manganese
pH
Fig.7 Influence of pH on the availability of plant nutrients in organic soils. Shaded areasindicate maximum availability.
Source: Lucas & Davis 1951
Strongly Stronglyacid Neutral alkaline
37
Assignments1. Collect samples of common chemical fertilizers and look for characteristics
which will help to identify them visually.
2. List the places where chemical fertilizers are available in your area.
l In plants, Zn is involved in enzymesystems, essential to proteinsynthesis and seed production.
l Zinc deficiency vary with crops. Inlegumes spots appear on olderleaves giving a mottled appearance.
l In fruit trees, rosetting appear atterminal points; narrow leaves withyellowing between veins.
l In cereals, yellow stripes appear inleaves; seed production is reduced.
l Fertilizer zinc has a long term residualbenefit.
Zinc fertilizers
l Zinc sulphate 36% Zn.
l Zinc EDTA 6 – 14% Zn.
Nutrient Interactions
l It is important to maintain a limitedrange of nutrient concentration forplant growth, through proper soilmanagement and fertilizer practices.
l High levels of one nutrient in the soilmay depress the uptake of anotherto make the latter a limiting factor forgrowth of the plant.
Examples of nutrientinteractions
l Excess copper adversely affects ironinteraction.
l Antagonism by iron and manganese;zinc and iron.
l High levels of P, induce zincdeficiency.
l Potassium and calcium inducemagnesium deficiency.
Synergistic nutrientinteractions
l N - Helps the uptake andutilization of all micronutrients.
l Mg - Increases P uptake.
l P - Favour Mo uptake.
38
ORGANIC MANURES
General features
l Bulky - Low bulk density.
l Low content of plant nutrients.
l Contains all essential plant nutrients.
l High application rates are necessary.
Types of organic manures
l Plant origin
l Animal origin
l City wastes
l Industrial wastes
l Composted materials
Fig. 8. Sunhemp
Plant origin
Green manures
l Two types
a). Grown in the field for insituapplication. Plants are ploughed atflowering due to high concentrationof N.
e.g. Crotalaria juncea (Sunhemp)
Sesbania rostrata
b). Leaves and tender stems loppedfrom trees are applied to soils afterploughing.
e.g. Gliricidia,Tithonia diversifolia (wildsunflower) etc.
l Most green materials could be used.
l Legume and composite plants havehigh N.
l Materials with high C:N are notsuitable.
l Should be applied and buried in thesoil.
Fig. 9. GliricidiaNote: See appendix 3 for list of green manure plants.
39
Crop residues
Crop residues such as rice straw, cornstover, grain stover and other crop stovercould be used. Grain husks, corn stalk andother materials could also be used.
l Crop residues such as straw havehigh C:N ratio. Therefore applicationto the soil before seeding has to bedone. C:N could be narrowed byaddition of N fertilizers.
l Requires adequate moisture fordecomposition.
l Residues of graminaceous cropssupply K and silica to plants.
Animal origin
l Includes dung, urine, grasses andfeed stuff, and bedding of animals.
l They have materials at variousstages of decomposition.
l Contains small amounts of plantmaterials.
l The amount of plant nutrientsdepends on
u Species
u Age of animal
u Feed given
u Nature of collection
Note: See Appendix 4 for livestockpopulation in Sri Lanka
Fig. 10. Wild Sunflower
Fig. 11: Rice straw application
Fig.12 : Cow shed with facility forcollecting dung
40
Animal dung
l Pure dung is seldom collectedseparately except from poultry inbattery cages.
l Animal dung has more plant nutrientsthan farmyard manure (FYM).
Poultry litterl Are of two types - Layer litter
- Broiler litter
l Layer litter cotains poultry excreta,feed material and feathers in asubstratum collected for over oneyear. This material is richer in plant-nutrients than broiler litter.
l Broiler litter is changed every 40-45days.
City wastes
l Collection of garbage fromhouseholds, factories, garages,markets, streets, slaughter housesetc. is referred to as city wastes.
l This material is allowed todecompose.
l The decomposed material iscollected, dried and sieved beforemarketing.
Industrial wastes fromagriculture
l Fruit and vegetable canning factorieshave waste materials.
Compost
l Is an inefficient method of convertingorganic material to a humus likematerial; about 40-60% of the N inthe material used for composting arelost.
l Composting regulates the bio-degradation process, enables valueaddition to waste materials andallows the recycling of plant nutrients.
l Composting could be carried out atthe domestic or industrial scale.
l Domestic composting allows thesystematic disposal of garbage andalso recycles this material on cropsor floriculture.
l The composting at industrial scalefocuses on waste management.
l City compost may contain heavymetals and pathogens if thecomposting procedure is not perfect.
Composting methods
Two types
l Aerobic
l Anaerobic
Aerobic method
l Air is allowed freely for full oxidationof the biodegradable material.
l No smell is found in the finishedproduct.
l The finished product has noresemblance to the original material.
Under the aerobic methodsmany forms are operated
l Raised beds - Heap method
l Dug in beds - Pit method with aprotective roof
l Barrel method
l Wormy compost
41
Anaerobic method
l Air is not used for the decompositionprocess.
l Finished product has an offensiveodour.
l Often the original material could beidentified.
l Has high moisture content over 85%.
Note: See Appendix 5 for organicmanures and their nutrientcomposition
Fertilizer use efficiency (FUE)
Fertilizer use efficiency (FUE) can bedefined in two ways. Soil scientists equateFUE with the percentage of the appliednutrients (through fertilizer) utilized by acrop.
Fig. 13. Heap method of compostmaking (aerobic method)
Note: See Appendix 8 for compostmaking methods
A FUE of 100% means the entire amountof fertilizer added to a soil is removed bythe crop. This is very unlikely becausefertilizer nutrients added to a soil undergofour types of disposal; they are
l Removed by the crop;
l Remain in the soil solution but is notremoved by the crop;
l Fixed to the soil and not available;and
l Lost through leaching and otherforms.
The FUE for nutrients like nitrogen (N) willbe limited to one season whereasphosphorus (P), potassium (K) and othernutrients will last for longer periods due toresidual effects. The FUE for N is generallyless than 50% while for P and K the valuesare often less than 15-20% for a growingseason of a crop. The residual effects ofP and K will last for a longer period andFUE for P and K at later stages may be aslow as 2-3%.
X 100=
Thus,
FUE = Percentage of applied nutrient utilized by the crop
Amount of fertilizer nutrient removed by the crop
Amount of fertilizer nutrient applied
42
Assignments1. Look for the availability of different manures of animal origin in your
area and list them.2. Search for manures of plant origin available in your area and list them.3. Prepare compost using materials available in the area.
From an agronomic point of view, FUE isdefined as the amount of produce per unitof applied nutrient. i.e.
YF - YO
FUE =N
where YF = yield of the fertilized treatment;
YO = yield of the unfertilized control;
and N = amount of applied nutrient.
The actual yield level and the response tofertilizer will be influenced by many aspectsof crop management.
43
Balanced Fertilizer Use,Soil Testing, Economicsof Fertilizer Use
CHAPTER 2
44
This chapter deals with, balanced fertilizeruse, its importance, law of the minimum,basis of fertilizer recommendation,adverse effects of imbalanced and overuseof fertilizer and manure, soil testing andeconomics of fertilizer use.
It is intented to achieve thefollowing broad objectives
1. To know the meaning of balancedfertilizer use, its importance, effectsof unbalanced and overuse offertilizer.
2. To get knowledge on soil testing andcollection of soil samples.
3. To get information on economics offertilizer use.
Section I
IMPORTANCE OFBALANCED FERTILIZERUSE
Introduction
The presence of adequate quantities ofnutrients in forms accessible to plant rootsin soil solution is essential to attain optimumcrop growth. Environmental factors andsoil plant nutrient content and its availabilitydetermine the capacity of a plant to absorbsuch nutrients. Soil fertility determines thecapacity of a soil to supply nutrients. Thecapacity of a soil to supply nutrientsdepends on many factors of which moisturecontent plays a big role.
Balanced fertilizer use
l Maintaining the balance between thecrop nutrient requirement and thecapacity of the soil to supply thesenutrient is the basis of balancedfertilizer use. Supplementing thesoil’s capacity to supply the croprequirement has to be done bymeans of adding chemical fertilizeror organic manure to the soil.
l An understanding of the nutrientrequirement is the most importantaspect of balanced fertilizer use.
l Plants have specific nutrientrequirements based on crop speciesand cultivars. Some species have ahigher requirement of certainnutrients. Cereals requires more Nwhile legumes require more availablephosphorus. Sugar cane, bananaand tomato require more potassium.
l In practice soils have the capacity tosupply calcium, magnesium andmost micronutrients. But enhancedcrop production limits the availabilityof these nutrients.
l Practical experience shows thataddition of sulphur, calcium,magnesium, zinc and boron arehelpful to certain crops. eg. tea andcocoa.
l Application of calcium at pod initiationfor groundnut is beneficial.
l Application of molybdenum forheading of cauliflower is important.
45
l Addition of zinc, magnesium andsulphur is necessary to sustain riceyields over 200 bu/ac.
l Balanced fertilization requires the useof both chemical fertilizer and organicmanure to supply the requirementof major, minor and micronutrients.
Effects of unbalancedfertilization on crop yield andsustainability
l When the elements essential forefficient plant nutrition and economicproduction are low in availability orunbalanced, then chemical fertilizersand soil amendments are required,to enhance crop yields.
l Incorrect fertilizer recommendationor unbalanced/inadequate availabilityof nutrients can lead to depletion ofsoil nutrient reserves and loss ofplant nutrients supplied in excess.
l Lack of balance nutrients alsoencourages excessive uptake ofthese nutrients supplied in excess,but with no benefit.
l Unbalanced fertilization is anuneconomic waste of scarceresources.
Importance of balancedfertilizer use
To maintain sustainable agricultural systemswhile achieving optimum yields, a supply ofadequate and balanced amounts of plantnutrients must be provided at the correcttime.
Balanced fertilizer application,
l Increases fertilizer use efficiency.
l Increases crop yield and quality.
l Improves nutrient value of the cropresidues, which can be used asmanure.
l Minimizes build up of high levels ofresidual nutrients, antagonisms andnegative interactions.
l Can reduce pesticide requirementsand produce healthier food.
l Reduces adverse effects of wastefulfertilizer application; i.e. eutrophica-tion, groundwater pollution or airpollution.
Adverse effects of imbalanced /overuse of chemical fertilizeron the environment
The role of fertilizer as a causal agent forpollution is widely acknowledged.
l Nitrate leaching and subsequentaccumulation in groundwater.
Effects of excessive use of chemicalfertilizers in the Regosols along thewestern coastal belt in the Kalpitiyapeninsula are well known. Thesesoils are used for the cultivation ofhigh-value cash crops such aspotato, onion and vegetables underlift irrigation. These soils contain over98% sand and as a result have verylittle water or nutrient retention ability.High accumulations of salts wererecorded from water drawn from
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wells used for irrigation, (10mg N/l,300-400 mg Cl-/l). The comparablevalue for nitrate N in non-cultivatedor lightly fertilized coconut lands wasless than 2 mg N/l. The averageannual increase in groundwaterchloride and nitrate-N concentrationswithin the intensively cultivated areawas estimated at 5 and 2 mg/lrespectively. This is equivalent in thecase of nitrate to a leaching loss rateof 60-120 kg N/ha/year. Thedeterioration of groundwater qualityand nutrient loss from such practiceswere unacceptably high.
In the Jaffna and Kilinochchi districtsin the northern Sri Lanka, a varietyof cash crops are grown undersupplementary irrigation. The majorsoils in the Jaffna peninsula are thecalcic red-yellow latosols, which areshallow, fine-textured and well-drained. In the Kilinochchi district,red-yellow latosols are interspersedwith alluvial soils of variable drainageand texture. Analysis of watersamples from 65 wells from the twoareas used for agricultural anddomestic purposes showed varyingdegrees of contamination. Thenitrate-N concentration in 79% of thefarm wells in Jaffna was higher thanthe WHO recommended safe valueof 11.3 mg/1. Wells used for domesticwater supplies had low nitrate levels.The wells in the Kilinochchi districthad very low nitrate – N content.
l Build-up of nutrients
Fertilizer application rates in theupcountry in relation to potato andvegetable cultivation are 3-4 timeshigher than the DOA recommenda-tion while application rates of animalwaste are as high as 10-65 t/ha. Asoil build-up of P and K levels manytimes higher than in the average soilswas observed in such areas. Olsenextractable P values ranging from25 ppm to well over 600 ppm and Kvalues from 0.1-1.5 meq K/100 g soilwere recorded. Due to the hilly terrainof lands used for vegetable cultivationnutrient leaching and accumulationin water bodies takes place easily.
Liebig’s law of the minimum
An excess of a particular nutrient overanother nutrient which is in short supplycould follow the phenomenon of the law ofminimum.
German scientist Justus Von Liebig (1803-1873) propounded the law of the minimumwhich states;
l If a particular element is deficient,plant growth will be poor even whenall other nutrient elements areabundant.
l If the deficient element is suppliedgrowth will increase.
l Increasing the particular elementmay not be helpful beyond this pointas another element will be in shortsupply and limit growth.
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Fig: 14 The law of the minimum as shown by a splintered barrel
Liebig illustrated the law as a wooden barrel with staves of unequal length. The capacityof the barrel is limited by the shortest stave(in this case, nitrogen) and can only be increasedby lengthening that stave. When that stave is lengthened, another one becomes the limitingfactor.
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Section II
SOIL TESTINGl Routine soil testing is done in farmers
fields to determine nutritional statusof soils and fertilizer needs. Testsare available to evaluate nearly allelements essential for plant growth.
l Soil tests produce best managementwhen used in conjunction with othergood farming practices.
l Samples must be taken deep enoughto give a good measure of the solublenutrients through out the crop rootingdepth.
l Soil tests give an index of nutrientavailability rather than a precisemeasure of the total amount in thesoil.
Soil Sampling
l Soil samples sent to laboratory mustrepresent that part of the field that isrequired to be tested.
l Follow the basic rules
i. Keep accurate records of pastfertilizer applications, crop yields, soilproblems etc.
ii. Use a proper tool like an auger,mammoty, spade, tube etc. to obtainsoil from the correct depth.
iii. Each sample must represent auniform soil area.
a) Narrow slope range, similarsoil colour, texture and depth.
b) Crop height and yield.
c) Wet or salty spots, erodedknobs etc.
iv. Avoid field variability due to :
a) Poor judgement in sampling.
b) Failure to clean tools betweensampling.
c) Contamination with non soilmaterial.
d) Inadequate mixing of subsamples.
Fig: 15 Sample soils on soil type and crops that were grown
Note : See sampling points in soil C
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l Sampling of fields once every twoyears is sufficient.
l Avoid sampling after application offertilizers, liming material or organicmanure.
Laboratory analysis
l Laboratories will analyze for thefollowing in routine analysis;
i. Soil texture
ii. Soil pH (measures acidity / alkalinity)
iii. Electrical conductivity (measuressalinity / alkalinity)
iv. Available P content (mmols 1-1)
v. Exchangeable K content (C mols /kg soil)
vi. Soil organic matter content (%)
l If further analysis is required onsecondary micronutrients, analysiswill be made on;
i. Calcium, magnesium and sulphate-sulphur
ii. Micronutrients except molybdenumand chloride. (Not included ingeneral analysis).
Plant analysisl Helps to determine sufficiency or
deficiency of plant nutrients throughthe analysis of various plant partslike leaves, stems or leaf petioles
l Time of sampling, age of plants,type of plant part to sample aredecisive in sampling.
l Plant analysis helps to determinetoxic levels of certain elements.
l Plant analysis verifies visualsymptoms.
l Plant analysis will not have anyrelationship as to what will happenfrom plant growth to maturity. Plantanalysis of annual crops will notpermit to carry out correctivemeasures.
Fertilizer application
l Generally all fertilizers are applied tothe soil before establishment ofcrops.
l Exception is nitrogen and under rareinstances potassium is recommendedas a top dressing.
l Fertilizers should be added to helpthe growing seedling / plant tocapture the material by roots.
l Banding, deep placement, sidedressing, top dressing are somemethods of fertilizer application.Always cover the fertilizer materialwith soil under upland conditions. Inpaddy-rice, cover the basal fertilizerwith a mud film. Top dressing shouldbe done with a small film of waterand retain the water for 2-3 days.
l Some fertilizers like urea and othersoluble salts could be applied as afoliar dressing in extremely dilutedconcentrations.
Fertilizer recommendations
Appropriate fertilizer recommendationsprovide plant nutrients needed to sustainmaximum production and profitability whileminimizing environmental impact of fertilizeruse. The knowledge of nutrient removal,nutrient uptake patterns by crops and
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capacity and availability of nutrients in thesoil reservoir helps to formulate correctfertilizer recommendations.
Fertilizer recommendations are based onmany assumptions, real experiments, dataanalysis, statistical analysis and field testing.
l Assumptions are based on plantnutrient removal based on upperground part analysis of most cerealcrops, tubers and fruits along withstems and leaves in other annualcrops. Plant tissues are dried, groundand representative samples areanalyzed in laboratories. Table 6gives information on rice cropremoval of plant nutrients.
l Based on this information the nutrientrequirement of a crop at a particularyield level could be evaluated.
l Fertilizer experiments are carried outto determine the response of a cropto one or more nutrients. Differentcombinations of plant nutrients atvarious rates are combined in theseexperiments. The best combinationand rate is assumed to give bestresults.
l Soil and plant analysis: Give anindication of what plant nutrients thesoil has in store,and the status ofnutrient concentration in the plant .
l Values arrived by all thesecombinations are tested both atresearch stations and farmers fieldsbefore fertilizer recommendations aregiven.
l Any chemical fertilizer recommenda-tion, should take into account thenutrient value of added organicmanure to avoid over supply.
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Section III
ECONOMICS OFFERTILIZER USEl Research has found that higher
yields are closely related to profitablecrop production.
l Higher crop yields help to reduceper unit cost of production and toobtain maximum profit.
l Proper use of fertilizers provides thegreatest opportunity for obtaininghigher yields.
l Fertilizer application complementsthe effects of other managementpractices and gives higher cropyields.
l Profit depends on the relationshipbetween cost of production, inputssuch as fertilizers and the increasedvalue of crop yield. An understandingof incremental cost and return isnecessary to determine this.
Economics of fertilizer use is the profit perunit area that is obtained by the addition offertilizer to a crop.
Increased use of fertilizer for a crop tendsto increase yield at an increasing rate, thenat a decreasing rate and finally moreaddition will infact completely decrease theyield. This is demonstrated by the law ofdiminishing returns.
Effect of fertilizer on yield ofRice
Table 4: Total production andmarginal production of rice(Hypothetical example)
Amount of Total product Marginalfertilizer (t/ha) product(kg) applied (t/ha)per ha.
0 2.4 -50 3.2 0.8
100 4.3 1.1150 5.6 1.3200 6.2 0.6250 5.1 -1.1
300 3.8 -1.3
Above table shows the effect of increasingfertilizer levels on the yield of rice. Marginalproduct increases with increase of fertilizerand then falls to zero and takes negativevalues.
Maximum yield and maximumeconomic yield
Maximum yield in the above example is 6.2tons/ha when 200kg of fertilizer is usedand the corresponding marginal product is0.6. When marginal product is zero yield isat its maximum.
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Fig.16, Relation between maximum yield and maximum economic (profit) yield
Yie
ld
Input
MaximumEconomicYield
MaximumYield
When represented graphically (Fig.16), atmaximum yield, the increase in output inresponse to the last unit applied is zero.However at the maximum economic yield,the value of additional output for the lastunit of fertilizer applied is equal to the costof that unit of fertilizer. In economic terms,the value of marginal product is equal tothe marginal cost. This is the point ofproduction at which the maximum profit isobtained. Up to this point adding one ormore units of fertilizer results in a netincrease in the total profit.
Beyond this point, the value of additionaloutput resulting from the addition of one ormore units of fertilizer is less than the costof fertilizer.
This shows that the point of maximum yieldis not always the point of maximum profit.Also, the point of maximum economic yielddepends on the level of management ofthe other inputs need for production.
Fertilizer application, cost ofproduction and net profit
The cost of production of crops continuesto rise due to increases in input prices.Crop prices often do not increase enoughto keep pace with production costs.Therefore, to remain profitable it isnecessary to lower the unit cost ofproduction. The most realistic means toincrease yields is the application of fertilizer.Application of fertilizer makes the cost ofcultivation per unit area (per acre) also togo up. However, the resulting increase inyield more than compensates for increasein cultivation cost and as a result, the unit(per kg or ton) cost of production is lowered.This leads to an increase in net profits fromcrop production. The decrease in unit costof production insures the grower againstprice declines. In other words, at higheryields, the price at which the crop can breakeven, is reduced greatly.
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Table: 5 Optimal Application of Fertilizer and Revenue (Hypothetical example)
Amount of Total Cost Marginal Total Total Marginal Net ReturnFertilizer of Fertilizer Cost (MC) Production Revenue Return (MR)
(kg) added (Rs) (Rs) (Kg) (Rs) (Rs) (Rs)
0 0 0 2400 24000__
2400050 400 400 3200 32000 8000 31600
100 800 400 4300 43000 11000 42200150 1200 400 5600 56000 13000 54800200 1600 400 6200 62000 6000 60400250 2000 400 5100 51000 -11000 49000
300 2400 400 3800 38000 -13000 35600
When marginal return is zero maximumcrop yield or maximum total return (revenue)is obtained, this is between 200 kg to 250kg of fertilizer. But the economic yield iswhen MC = MR which may be above 200kg
level but of course below 250kg. At thispoint net return is at maximum and theoptimum profit is obtained, indicating thatexcessive use of fertilizers is not giving aneconomic return.
Fig. 17 Relation between economic (profit) yield and level of management
IMPROVEDMANAGMENT (B)
AVERAGEMANAGMENT (A)
PROFITDIFFERENCEA VS B
FERTILIZERCOST
LEVEL OFFERTILIZER FORMAXIMUMPROFIT
COST OF FERTILIZER
B
A
AMOUNT OF FERTILIZER
YIELD/VALUE
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Likewise, per unit cost of nutrients infertilizer mixtures is usually higher thanthat in straight materials. However, the costof mixing, transporting and applying mustalso be considered in comparing the twosources.
Use of organic manure
The use of organic manure, when cheaplyavailable is a good alternative to chemicalfertilizer use. However, due to limitedavailability and handling costs, organicmanure has limited potential under mostsituations.
Due to other benefits such as supply ofmicronutrients and organic components thatincrease soil moisture retention and reduceleaching of nutrients, organic manure givesgreater benefits than chemical fertilizers.
Therefore, when conditions permit, it isbeneficial to use organic manure in cropproduction.
Note: See Appendix 9 for Economics ofIPNS
As shown in the Fig. 17 the maximum profitunder average management is at point Aand under improved management atpoint B.
Also, because the maximum economic yieldis dependent on the value of production,any changes in the relative prices can affectthe point of maximum profit.
When the price of output increases with thefertilizer price remaining constant, thefertilizer rate for maximum profit increases.
Alternatively, if the fertilizer cost increasesat constant crop price, the fertilizer rate atmaximum profit declines.
Economics of nutrient use
Also, in the application of fertilizer it isnecessary to consider the most economicalsource of nutrients than the per unit (kg)cost of product.
Often urea is the most economical sourceof providing a unit of N than alternativessuch as ammonium sulphate or ammoniumnitrate.
Assignments:1. Collect a sample of soil from a farmer’s field in your area on the basis
of principles given.
2. Study the DOA soil testing programme for farmers in your area.
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CHAPTER 3
Integrated Use of
Organic Manures andChemical Fertilizersand Principles
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INTEGRATED USE OFORGANIC MANURESAND CHEMICALFERTILIZERS ANDPRINCIPLES
This chapter is on Integrated PlantNutrition Systems (IPNS) and concernswith its definition and its objectives.Practices of IPNS by farmers and prosand cons of using chemical fertilizer andorganic manure, IPNS versus organicfarming are also dealt. Socio-economicsof IPNS, its impact on the environment,limitations of organic manure use, itspractice in different cropping systems andthe constraints of its practices in Sri Lankaare also discussed.
It is expected to achieve thefollowing broad objectives
1. To know the meaning of IntegratedPlant Nutrition and objectives ofIPNS.
2. To know what went wrong withchemical fertilizer use.
3. To compare the use of chemicalfertilizers with the use organicmanure.
4. To familiarise with organic manureapplication and to know limitations.
5. To provide knowledge on organicfarming against IPNS, managingnutrient balance in IPNS, socio-economics of IPNS and its impacton the environment.
6. To know IPNS practices for differentcropping systems and drawbacksof IPNS in Sri Lanka.
INTEGRATED PLANTNUTRITION SYSTEMS (IPNS)
Definition of IPNS
l Integrated Plant Nutrition System isa holistic approach to plant nutritionby obtaining the nutrients from bothinorganic and organic sources tomaintain and sustain soil fertility andenhance crop productivity in aframework of an ecologicallycompatible, socially acceptable andeconomically viable situation.
Need for integrated use
l Organic manures sustain soil fertilityat a low level of production.
l Chemical fertilizers haveconcentrated forms of nutrients.Application results in leaching,fixation and build-up of certainnutrients at the expense of others,resulting in nutrient imbalances.
l Fertilizer use efficiency (FUE) is lowin all chemical fertilizers and organicmanure when used singularly.
l Combined use of organic manuresand chemical fertilizers increasesFUE
Objectives of IPNS
l Increasing the fertilizer use efficiency.
l Increasing the return to investmenton fertilizers.
l To use a balanced system of cropnutrition management.
l To account for the different amountsof plant nutrients, in a budget sheetgiving the following:
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1. Available in the soil.
2. Available from organic sources.
3. Available in crop residues.
4. Derived from biological fixation.
5. Derived from fertilizers and theirresidual effects.
When preparing a budget, a whole croppingsystem is looked into than a singular crop,over a long term.
What has gone wrong infertilizer use?
l Before chemical fertilizers wereintroduced, organic forms were used.
l Green manures, crop residues andFYM were used in large quantities.
l A season of farming was followedby a fallow period for replenishmentof soil fertility.
l Chemical fertilizers suppliedsufficient plant nutrients for obtaininghigh yields. These fertilizers did notprovide the crop requirement of allnutrients.
l The continuous use of chemicalfertilizers destroyed the soil structure,turned the soil acidic and broughtabout nutrient imbalances resultingin nutrient interactions.
l The organic matter in the soil did notimprove with application of chemicalfertilizers resulting in erosion and lossof top soil.
l The yield increases obtained duringthe early years of chemical fertilizeruse evened out and addition ofextra fertilizers did not bring thedesired benefits.
Farmer practices of IPNS
l Vegetables, potato and green leafyvegetables are cultivated using bothorganic and chemical fertilizers.
l Here farmers obtain higher yieldsthan farmers using either chemicalfertilizers or organic manures.
l Extension of this practice to othercrops has resulted in increases ofyield and sustainability of productionat a higher level.
Chemical fertilizers or organicmanures
l To sustain crop yields, the rate ofremoval has to be balanced byadded amounts. Use of chemicalfertilizers is necessary for supplyingthe nutrient requirement but withoutrecycling of crop residues, yields willsuffer.
l If only organic manure is used landwill benefit but yield will be lower.
l Availability of nutrients from organicmanure is slow but long lasting.
l Use of organic manure improves thephysical, chemical and biologicalconditions of the soil.
l Singular use of chemical fertilizershas an adverse effect on the soilstructure. If the organic matter is lowthe bulk density increases.
l Use of chemical fertilizers along withorganic manure gives a soil rich innutrients with good physical andmicrobiological properties. This willincrease the availability of nutrients.
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l Application of organic manure resultsin formation of water stableaggregates which could resisterosion.
l Combined use of chemical andorganic fertilizers increases cationretention and improves nutrientavailability.
l Addition of manure widens the C:Nratio in soil. Singular use of chemicalfertilizers narrows this ratio.
l Addition of mineral N fertilizers resultsin instant increases of N but organicmanures increases the available N.
l Fixation of fertilizer P could bereduced and effectiveness of fertilizerK can be increased when chemicalfertilizer is combined with organicmanures.
l High analysis fertilizers have lowcontents of micronutrients, butcombined use with organic manuremakes these nutrients available toplants.
l Combined use of manure andchemical fertilizers results in higherreturn to investment and bettercost-benefit ratios.
l Thus it is beneficial to use bothmanure and chemical fertilizers forcrop production.
Organic farming or IPNS?
l Organic farming systems do not useany synthetic form of plant nutrient.Italso avoids the use of pesticides andweedicides. Organic manure ofanimal origin should not have artificialingredients fed to animals andanimals should not be treated withantibiotics or steroids as growthpromoters.
l Obtaining green manurecontinuouslyfrom trees results in removal of plantnutrients from soils, which are noteasily replenished. This results inpoor growth of the green manuretrees itself, which could result in ashort fall of supply of the material.Thus a limitation to resourcemanagement occurs.
l Organic farming maintains theproductivity at a low level. Wheredemand for food is becoming moreincreasing organic farming per secannot meet the required demand.
l Plants obtain nutrient sources in theionic form. Whether they come fromorganic or inorganic forms, the typeof ions is the same.
l It is best to combine the use of bothmanure and mineral fertilizers ratherthan manage the singular use ofmanure.
Managing a nutrient balance inIPNS
l IPNS attempts to keep a balancebetween crop removal and nutrientaddition to the soil. In this respect abook keeping exercise has to beginwith the first step of how much thesoil already has.
l Soil analysis for evaluating thenutrient availability and its limitationsthat could reduce the productivity,has to be done at the begining.
l The yield goal of the cropping systemof single or multiple crops that wouldbe grown over time (say one year)has to be evaluated to arrive at thenutrient removal.
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l The quantity of mineral fertilizers tobe applied has to be decided on soiltest values for P and K.
l The addition of organic manures tosupplement the requirement of theminor and micronutrients has to beevaluated.
l Nitrogenous fertilizers to be used oncrop demand rather than on blanketrecommendations has to bepractised.
l Limitations to FUE by drought,surface erosion, poor drainage areto be avoided.
l Correct application practices in basaland top dressing applications of bothorganic and chemical fertilizer haveto be adopted.
l Crop residues have to be recycledto supplement the nutrient pool ofthe cropping system.
l If legumes are included in thecropping system, credit has to begiven for possible biological nitrogenfixation (BNF).
Socio economic side of IPNS -Scope and limitations
l Any IPNS practice has to beeconomically sound and sociallyacceptable. Organic manure shouldbe available easily in acceptableforms and types.
l Crop residues are often burntinstead of recycling. Scarcity oflabour, and the time gap betweentwo crops may limit the use.
l Organic manure for many farmers isnot available in their own holdings.The holding size often limits animalhusbandry. Transported material istoo expensive and transport to thefarm is laborious.
l Chemical fertilizers are easilyavailable and literature on their useis more comprehensive. Organicmanure and crop residuemanagement has not been given thesame importance.
l Use of FYM, poultry litter and otheranimal wastes is popular amongfarmers. But sewage, sludge andurban compost are not popularamong them.
l Financial credit is available only formineral fertilizers. There is noorganized credit system to help thefarmers to use organic manure andcrop residues.
l Chemical fertilizer market iscontrolled with a standard productbut organic manure is sold withoutany standards.
l Storage and retail marketing oforganic manure is limited. It is noteasily accessible to most farmers.
l Farmers who have domesticatedanimals do not have facilities tocollect,store and market the animalwaste.
l The scope for IPNS is limited to afew high value crops in the presentcircumstances. Farmers growingthese crops may be encouraged tofollow IPNS.However, a large numberwho have access to organic manuredo not use them.
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IPNS and the environment
l Chemical fertilizers are consideredto be environmental pollutants.Nitrogen fertilizers when used inexcess can be leached or washedthrough erosion into waterways andreservoirs. Eutrophication ofreservoirs have been reported fromtime to time.
l Nitrogeneous compounds inorganic manures too are convertedto nitrates. Any excessive use andleaching could bring the sameenvironmental hazard as usingexcessive amounts of urea orammonium sulphate.
l Nitrogen fertilizers can acidify soils,but when used with organic manurecan buffer acid formation to acertain degree.
l Liming can change the pH andimprove CEC. Liming can be acorrective measure to improve thecrop environment.
l Excessive build-up of P and K insoils results in nutrient interactions.In high P built-up soils, both zincand copper availability can be aproblem. At high levels of K in thesoil, magnesium becomes limiting.By following IPNS these excessescan be cushioned.
l Excessive use of organic manurescan limit the availability of copperas the latter is lost through leaching.Following IPNS will benefit thesituation.
l Combined IPNS, benefits thedevelopment of soil structure andreduces erosion hazards.
l IPNS practices produce more healthyplants which minimizes the necessityto use pesticides and fungicides,which are harmful to the environment.
l Excessive nitrate leaching intogroundwater and drinking water isharmful. IPNS can increase the anionretention when mineral and organicfertilizer is used together.
l Ploughing and land preparation iseasy on lands following IPNS.Ploughing deep to expose the sub-surface soil does not arise in theselands.
IPNS and fertilizer useefficiency
Chemical fertilizer in the form of salts, whenadded to soils gets converted into ionicforms after dissolving in the soil solution.Substances like urea under go extra cellularenzymatic decomposition to formammonium compounds, which are eitherabsorbed by the plant roots or convertedto nitrates, which are absorbed or lost inleaching or converted to gases in the Ncycle.
Organic manure produces organic acids(humic acid) which have the capability ofholding cations and anions. Soils rich inorganic matter can hold more cations thanotherwise. Ammonium ion like other cationscan be adsorbed to organic acid moleculesafter replacing H. This adsorption helps torelease the cations slowly to the plants. Ifnot for the organic molecules certainchemicals reactions can make mostnutrients unavailable to the plants.
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Most plant nutrients are available at certainpH ranges. Addition of organic manurescan buffer pH, making more materialsavailable to plants. Soil organic matter hasa high CEC values and CEC is pHdependent. If liming is done to increase pHthen the CEC will also increase. The CECfrom organic manure is temporary.
Organic manure applicationand limitations
l Organic manures are of plant andanimal origin.
l Plant materials have easily andslowly biodegradable materials. Thevariety, age and plant part determinethe composition and the quicknessof decomposition.
l Younger leaves and tender stemshave more water, more N and lessother minerals and decompos faster.Matured leaves and stems havemore cellulose containing material,which takes a longer time todecompose.
l Crop residues such as straw havemature tissues with high C:N ratio.They take a longer time todecompose. Direct application willcause the temporary immobilizationof soil N.
l Animal wastes have more N thanplant parts. They decompose fasterthan plant materials. Application ofN rich materials like blood meal willresult in losses of N throughvolatilization.
l Composted material is suitable fordirect application. But exposure ofsuch materials to the elements
results in nutrient losses throughleaching.
l Care should be taken in using urbancompost made out of sewagematerials and industrial wastes.Such materials could contain bothpathogenic microbes and heavymetals.
l Heavy metals such as cadmium,arsenic, lead and mercury are toxicto environment. These heavy metalsare known to accumulate in the body.
l Organic manure decomposes fasterin the soil. A crop residue takes oneto two weeks to decomposedepending on the moisture contentof the soil and the type of material.Manure of animal origin decomposeswithin a few days.
l Application of organic manure shouldbe timed in such a way to get themaximum benefits both in terms ofplant nutrient supply and the additionof the carbon source.
l Incorporation to the soil is better thanleaving at the surface. Some farmersgive top dressings of well-decomposed manure, to crops.
l Poultry litter should not be appliedimmediately before seeding ortransplanting as the ammonia gasreleased may increase the pH andkill the plants.
l Well-dried organic manure can bekept for a few months in polyvinylbags.
l Liming should be done before addingorganic manure in order to conserveN.
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l Organic manure application to ill-drained soils could result in theformation of toxic compounds;particularly if the material is rich insulphur.
l Recent findings indicate that ricestraw can be added to bog soils. Thesilica content of the straw benefitsthe soils.
INTRODUCTION TO IPNSPRACTICES FOR CROPS ANDCROPPING SYSTEMS
Suitable organic materials forIPNS
Many materials that are organic in natureare suitable for IPNS. Materials that can beused are classified into:
i. Plant residues - Crop residues
Green manure
ii. Animal wastes - Animal manure
Slaughter housewastes.
iii. Compost - Consists of bothplant andanimalmaterials whicharewastes which alsoincludes citygarbage.
Crop residues
Rice straw, corn stover and vegetableresidues can be applied directly or aftercomposting. Direct application iscumbersome and due to high C:N ratio ofthe materials, it takes a longer time todecompose in the soil.
Green manure
Are of two types
l Which are grown in situ and ploughedinto the soil.
l Lopped leaves and tender stemswhich are applied to the soil.
Grown insitu
Plants like Crotalaria juncea and Sesbaniarostrata can be grown before establishingcrops and ploughed in at flowering duringland preparation. Soils with low content soilorganic matter will lose more carbon if Nhigh green manure is used.
Animal wastse
l Animal dung and urine of largeanimals found mixed with beddingand feed stuff are used as farm yardmanure (FYM). Poultry litter can beused both as a basal and topdressing. The material content of theFYM and litter varies considerablydepending on many factors.
l Slaughter house wastes and fishmeal are not available in Sri Lankain large amounts due to poorcollecting facilities. If collected andtreated properly it could become andimportant source of organic manure.
City wastes
City garbage can be composted and used.It is high in extraneous materials like silicabut is a useful material if properlycomposted. It can be used for floricultureand fruit culture in places close to cities.
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Above materials are available for IPNS.The quantities that may be ideal forapplication would be comparatively largerthan the rates of chemical fertilizer. But itis important to add any available amountof organic material available at appropriatetimes.
Some IPNS practices followedin Sri lanka
Rice-Rice Cropping Systems
l Straw recycling is followed. The strawleft behind after the previous crop isadded to the next crop atrecommended rates. Over 12-15%increases in yield are obtained.
l Supplementing straw recycling withcowdung at 2 t per ha. has increasedthe yields to 7.0-8.5 t per ha. Thisyield could be sustained throughcontinuous application.
l Farmers of Matara district add 1-1.5t of poultry litter per acre and20%-40% yield increases have beenreported.
l Farmers who use mineral fertilizersalong with cowdung at 2t per/ac.,green manure and burnt husk havegiven 10-10.5 t per/ha . These yieldscan be sustained through continuousapplication.
Rice – Other Field Crops (OFC)Cropping Systems
l Rice straw is added as mulch forchilli, onion, and vegetable crops.Addition of organic manure in theform of cowdung, goat dung orpoultry litter is practised.
l Higher yields and less crop damagedue to pests are reported.
Other Field Crops (OFC) - FoodCrops Cropping Systems
l Chilli and onion farmers extensivelypractice the combined use of mineralfertilizers and organic manure.
l The farmers who have used largerquantities get better yields and qualitycrops.
l Farmers who have practised theaddition of cowdung to irrigated andfertilized kurakkan have obtainedyields of 1800-2000 kg. per acre inthe Moneragala district.
Vegetable – VegetableCropping Systems
l Up country farmers often over useboth mineral fertilizers and organicmanures. Amounts of 30-40 t/ha ofFarmyard manure (FYM) are usedwith three to four times therecommended rates of mineralfertilizers.
l Farmers who cultivate ‘Keera’vegetables - use FYM, poultry litterand even pig dung to supplementthe mineral fertilizers.
l Most farmers who venture intocommercial vegetable production,use organic-inorganic fertilizercombinations. By this they get highyields than farmers who use onlyone of them.
l Farmers who cultivate ‘Innala’ useorganic – inorganic fertilizercombinations.
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Other crops
l ‘Kiriala’, pineapple and banana cropsare generally cultivated using mineralfertilizers. Farmers who have usedorganic sources in addition to mineralfertilizers have obtained better yieldsand quality products.
l Farmers growing ginger atcommercial level follow IPNS toobtain higher yields.
Some shortcomings of IPNSpractices in Sri Lanka
l Farmers following straw recycling inrice-rice cropping systems skip a fewseasons-due to socio economicreasons. By this, the necessaryfertility build-up is retarded.
l Some farmers expect a overnightyield increases through strawrecycling after the first season ofapplication. Not finding this, somegive up.
l Straw is generally not applied to rice-fallow systems.
l No importance is given to therecycling of crop stover of maize,chilli, onion etc. This depletes theorganic carbon in the soil.
l Certain vegetable farmers build upman made soil profiles by bringingnew earth to fill the top soil.
l Farmers who go for high intensivevegetable production often applymicronutrient solutions as foliarapplications. The imbalance of plantnutrition may have necessitated themto do so.
l Fertilizer practices carried out onsandy regosols of Kalpitiya haveshown groundwater pollution. Theoveruse of N fertilizers hascontributed to this. Addition of organicmanure may not be the best way toreduce pollution. A more nutrientefficient FUE approach has to befollowed.
Assignments1. Study the present adoption of IPNS in your area in different crops and
cropping systems.
2. List main sources of plant nutrients applied by farmers in your area.
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IPNS for Rice, Vegeta-bles,Chilli, Onion, Maize,Fruits,Root and Tuber Crops
CHAPTER 4
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Section I
IPNS FOR RICE
This chapter concerns with the majorcereal crop of Sri Lanka which is rice.The chapter consists of generalinformation on rice cultivation, nutrientremoval by the rice crop, rice growingsoils, and associated problems, ricebased cropping systems, fertilizerrecommendation for rice and IPNSpractices.
It is expected to achieve thefollowing broad objectives.
1. To provide information on generalaspects of rice cultivation in SriLanka.
2. To know nutrient removal by therice crop, and proven IPNSpractices and assoiated problemsin rice growing soils.
3. To provide information on ricebased cropping systems practicedin different agro-ecological zones.
4. To know present fertilizerrecommendation, and suggestedIPNS practices.
Introduction
l Rice is the main cereal crop grownin Sri Lanka; it is grown under diverseenvironmental conditions; fromdrought prone areas of the dry zoneto water logged and flood proneplains of the wet zone.
l Rice is grown in flat valleys almostat sea level to highly dissected
terrains up to 1000 m above sealevel. The temperature range variesfrom 170c to 400c.
l Due to the diversity of theenvironment and the soil conditionsa number of growing systems andcropping patterns have beenidentified, like the ‘Kekulan’cultivation, and the ‘meda’cultivation etc. Cultivars used, cropduration and yields obtained varyaccording to these patterns andsystems.
l Reported national average yield is3.78 t/ha. But farmers who havepracticed IPNS have obtained yieldsover 10 t/ha and sustain that level ofproduction over the years.
l Under good management anaverage yield of 6-7 t/ha is easilyachievable.
l IPNS practices that are in use arethe application of rice straw, greenmanure, dried cow dung/poultrymanure, ‘charred’ rice husk andchemical fertilizers.
l Improvement of chemical, physicaland biological status of the ricegrowing soils, have been achievedusing IPNS.
l More than 90% of the cultivars grownin Sri Lanka are 'New ImprovedVarieties' (NIV) with yield potentialsover 10 t/ha. These yields arepossible under favourable growingconditions.
l Rice cultivars are classified basedon time taken from seedling tomaturity.
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Long aged (5 – 6 months) photoperiodic sensitive ‘Ma-Wee’Medium aged (4 – 4 1/2 months)Short aged (3 – 3 1/2 months)
l Current fertilizer recommendationsfor rice are based on Agro EcologicalZones (AEZ), soil texture, cropmanagement and age of cultivar.
l Urea is the chief source of N, and theincorporation of urea is found toimprove N efficiency.
Fig. 18: Demonstration to obtain 200 bushels of rice per acre using IPNS
Nutrient Removal in RiceCultivation
Rice is an annual crop and it removes aconsiderable amount of nutrientsproportional to the yield obtained. Higherquantities of potassium and silica are foundin the straw and rice husk.
Table 6. Typical N, P, K, and Si content in rice straw and amounts removedby grain and straw in a 5t/ha crop (dry matter basis)
Nutrient Content (%) Removal (kg) by a crop Total removalyielding 5t/ha grain (kg/ha)
Straw Grain Straw Grain
N 0.74 1.26 37 63 100P 0.10 0.26 5 13 18K 1.81 0.32 90 16 106Si 5.00 1.70 250 85 335
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PRESENT SITUATION OFFERTILIZER USE IN RICECULTIVATION
A major portion of fertilizer used in Sri Lankais for rice. The fertilizer consumption patternfor the recent past shows that the Sri Lankanrice farmers use the recommended level ormore than that of N for rice. But P use isabout half the recommendation and the Kuse is three fourth of the recommendation.This shows an imbalance fertilizer use inrice cultivation.
Secondary or micronutrients are notgenerally recommended for rice cultivationin Sri Lanka and present studies show thatthere is a yield response to S, Zn and Cuapplication.
N application
Rice is very highly responsive to Napplication. Responses to N applicationvary with soil type, landscape, and cropduration and management conditions. As athumb rule to produce 20 kg of rice, additionof 1 kg of N is needed. The N use efficiencyin Sri Lanka is less than 30% due to highleaching and volatilization losses.Therefore, split application and soilincorporation are essential to increase theefficiency. Basically 3-4 split applicationsare recommended depending on the ageof the variety. Generally urea should bemixed with soil after application to increasethe N use efficiency. It is recommendedthat basal application of urea should bethoroughly mixed with the soil at the finalland preparation.
Supplementary application is recommendedif the crop management conditions are highwith assured water supply. N should beapplied to keep the leaf N content above2.5%. This is particularly important at theheading stage and soil should be at fieldcapacity. Weed free fields should beensured and the soil should be maintainedat field capacity before N application.
P application
Generally rice soils in Sri Lanka are low inavailable P. The responses to P applicationvary with soil type, pH and agro-ecologicalzones. The optimum response to Papplication in the dry zone is about 25-30kg P
2O
5/ha and in the wet zone it ranges
from 30-80 kg P2O
5/ha depending on the
soil type and soil pH. P application isgenerally recommended as a basal dressingand should be applied at the final landpreparation and should be thoroughly mixedwith the soil.
K application
Rice is one of the crops whichpredominantly absorb K. Response toadded K in Sri Lanka vary with agro-ecological zone, soil, water supply, cropyield and season. Generally K is applied asa basal dressing for all rice crops. Butadditional K is recommended for iron toxicsoils. Recently, additional K has beenrecommended if the targeted yields arehigh (more than 5t/ha.) to maintain soilfertility. Sufficient K (above 1.5% in leaf drymatter) after flowering is necessary tofacilitate carbohydrate translocation, whichenhances the grain filling to give anincreased 1000 grain weight.
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PROVEN IPNS PRACTICES INRICE PRODUCTION FOR THELOW COUNTRY DRY (DL) ANDINTERMEDIATE ZONES (IL)
l Falling soil fertility of rice growingsoils due to many reasonsnecessitates the use of IPNS toincrease production.
l Application of chemical fertilizersalone cannot increase yields beyondthe 6 t/ha limit.
l Addition of rice straw has improvedthe situation. Yields of 6.0 – 7.0 t/haare possible with combined rice strawapplications and recommended NPKapplications.
l Addition of organic materials peracre.
i. Two tons of dried cow dung.
ii. Total weight of rice straw of theprevious crop.
iii. Two hundred and fifty kg of charredrice husk
iv. One ton of green manure (Glyricidia,Ipil-Ipil, Tithonia etc.) had beenrecommended per acre tosupplement the chemical fertilizersadded.(N composition in leaves ondry basis in such materials shouldbe greater than 3%).
l Basal application of 50 kg TSP and50 kg. MOP along with 20kg of ureaper acre.
l Supplementing the NPK with ZnSo4
one kg/acre to meet the requirementof zinc.
l Rate of urea increased to total of130-140 kg/ac. to meet the Ndemand.
l The utilization of this package withthe following ensures a yield of180-200 bu/ac.
i. Quality seed paddy of provencultivars of;
(a) BG 357, BG 358, BG 360, BG379/2, BG 352
(b) AT 354
ii. Closer spacing at 10 cm x 10 cmplanting or 3 bu/ac for seed sowing.
iii. Proper irrigation, weed control etc.
l Direct application of rice strawwithout any addition of Nitrogeneousmaterials to narrow the C : N ispossible.
l Rice straw in small heaps should beevenly placed on levies, before landpreparation.
l Impounding of water results inimbibing and loss of tensile strength.
l After land preparation the heaps aredistributed evenly on the levies andincorporated to the soil with thesecond ploughing.
l Other organic materials should beadded after the second ploughing.
RICE GROWINGENVIRONMENTS
Diverse rice growing environments occurin Sri Lanka. Generally most of the soilsare low in available P and exchangeableK. In addition soils in the dry andintermediate zones are low in organic mattercontent.
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Associated problems in rice growing soils
Agro-Ecological Zone Soil Type Associated Problems
1. Low Country Reddish brown earths Presence of a shallow gravel layer, very Dry Zone hard when dry, sticky when wet, ( DL) salinity due to poor drainage conditions
in certain areas. Rice is grown inmoderately to imperfectly drained soils.
Low humic gley soils. Deep soil, ground water table close tothe surface, hard when dry, stickywhen wet, salinity due to poor drainageconditions.
Non calcic brown soils. Poor in water retention and nutrients,salinity due to poor drainage specially inMahaweli System B.
Red yellow latosols. Low water holding capacity and highleaching losses, salinity problems incoastal areas.
Alluvial soils. Deep soil, coarse soils are low innutrients and water holding capacity.
2. Low Country . Red yellow podzolic soils. Low CEC, poor nutrient status Intermediate Zone and high leaching losses. Iron (IL) toxicity may occur in certain
areas.
Low humic gley soil. Iron toxicity in certain land classes.
3. Mid Country Immature brown loams/ Iron toxicity occur in valleys(first or Intermediate Zone Reddish brown latosolic second order Reddish brown latosolic (IM) soils. soils.) P deficiency common in third
order valleys.
4. Mid Country Immature brown loams/ Iron toxicity and P deficiency very Wet Zone Reddish brown latosolic common. (WM) soils.
5. Up Country Red yellow podzols. No major constraint other than water Intermediate Zone availability. Steepness of land is a (IU) problem.
6. Low Country Mineral soils/Red yellow Iron toxicity, P, Mg Ca and exchange- Wet Zone podzolic on laterite/Alluvials able K very low. Salinity in coastal (WL) rice lands.
Bog soils. High organic matter with poor drainage.Flooding in coastal areas. Salinity, irontoxicity in certain areas.
Note: See appendix 6 for agro ecological zones (map)
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1. LOW COUNTRY DRYZONE (DL)
Cropping Systems
i. Rice / Rice croppingsystem
Major crop is rice, This system ismainly found in major and minorirrigation schemes with assuredwater supply. Rice is grown both inmaha and yala seasons.
ii. Rice / Other Field Crops(OFC) cropping system
Major crops are rice during mahaand chilli, onion during yala. Thissystem can be found in some majorirrigation and minor irrigationschemes as well as in rainfedconditions. Shortage of water in yalaseason limits ricec u l t i v a t i o n . B u t ,shortage of wateroccurs in certainrainfed areas; therebythe farmers adoptKekulan cultivation(dry ploughing) duringmaha season toconserve water.
iii Rice / Fallow croppingsystem
Major crop is rice which is mainlyrainfed. Maha rain is sufficient for ashort aged rice crop, but yala rain isnot sufficient for rice or any otherOFC.
Organic manure sources
Available organic materials are rice strawand green manure. Recommended strawapplication rate is about 4-5 t/ha. and greenmanure is recommended 2-3 t/ha.Application of cowdung is 5 t/ha. Poultrymanure can also be applied at the rate of3 t/ha. Charred rice husk can be applied atthe rate of 625 kg/ha.
Fig. 19 Stray cattle do not contribute much to IPNS
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Recommended fertilizerpractices
(Refer DOA fertilizer recommendation forrice)
Farmer practices of IPNS
l Recycling of rice straw with chemicalfertilizer
l Use of cow dung and poultry manure
Suggestions for improving thepresent systems of IPNS andfertilizer use efficiency (FUE)l Planting of Gliricidia, or Ipil Ipil on
the major bunds and hedge rows tosupply green manure.
l Use of charred rice husk.
l Cultivation of sandwich crops.
Fig. 20: Straw recycling
Assignments1. List organic materials available in the area for use in IPNS programme in
rice.2. Give your opinion of not using available organic materials for IPNS in rice.
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2. LOW COUNTRYINTERMEDIATE ZONE (IL)
Cropping Systems
i. Rice / Rice
Major crop is rice and mainly found in majorand minor irrigation schemes and underrainfed conditions.
ii. Rice / Other Field Crops
Major crops are rice, green gram, cowpeaand black gram. There may be a watershortage during yala season; these farmerspractice Kekulan cultivation for earlyestablishment of the crop.
iii. Rice / Fallow
Similar to rice/fallow system found in thedry zone.
Organic manure sources
Green manure is prevalent as Gliricidia.Mee, Keppetiya, Ipil Ipil and Sooriya.Application rate is about 4-5t/ha of greenmaterials. Apply crop residues at 2.5 to5 t/ha. Cowdung 5t/ha and poultry manure3t/ha and paddy husk charcoal 625 kg/hacan be applied.
Recommended fertilizerpractices
(See DOA fertilizer recommendation forrice)
Farmer practices of IPNS
l Recycling of rice straw
l Use of cowdung and poultry manure
Suggestions for improving thepresent systems of IPNS, andFUE
l Use of green manure and cultivationof Gliricidia and Ipil Ipil around thefields as green manure.
l Growing of sandwich crops.
l Use of charred rice husks.
Fig 21: Preparation of charred rice husk
Assignments1. List different organic materials available for IPNS in rice in the area.
2. Suggest ways of increasing the available materials for IPNS in rice.
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3. MID COUNTRYINTERMEDIATE ZONE(IM)
Cropping Systems
I. RICE /RICE
Major crop is rice and short aged ricecultivars are cultivated during yalaseason due to water scarcity.
II. RICE / VEGETABLE
Major crops are rice and vegetables.Yala rains are not sufficient for a ricecrop. Well drained soils are used forvegetable cultivation.
Organic manure sources
Available organic materials are rice straw,rice husk and green manure (Gliricidia, Wildsunflower, Ipil Ipil, ‘Kekuna’), and animalwaste.
Recommended fertilizerpractices
(See DOA fertilizer recommendation forrice)
Farmer practices of IPNS
Farmers use rice straw as the main sourceof organic manure, and rarely use cowdungor poultry manure for their rice crops, butuse these materials often for vegetablecultivation. Farmers also use green manurecrops as organic manure, in smallquantities.
Suggestions to improvepresent system of IPNS andFUE
l Use of both rice straw and chemicalfertilizer.
l Use of available green manureplants.
l Use of cow dung and poultry manureto supplement chemical fertilizer.
l Cultivation of legumes andincorporation of crop residues.
l Use of charred rice husk.
Fig. 22: Why burn rice straw ?
Assignments1. Study various organic materials use for rice in the area.
2. What are the IPNS practices done by the farmers of your area.
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4. MID COUNTRY WETZONE (WM)
Cropping Systems
Rice /Rice
Major crops is rice which is grown in bothyala and maha seasons.
Organic manure sources
Available organic materials are rice straw,green manure (Gliricidia; Wild sunflower,Ipil Ipil, Kekukna, Kaduru) and animalwastes such as poultry manure.
Recommended fertilizerpractices
(See DOA fertilizer recommendation for rice)
Farmer practices of IPNS
Farmers use rice straw as the main sourceof organic manure and rarely use cowdungor poultry manure for their rice crops, butthey use these materials in large amountsfor vegetable cultivation.
Some farmers use green manure crops asorganic manure sources but not in bigquantities.
Suggestions to improvepresent system of IPNS andFUE
l Use of rice straw along withrecommended levels of chemicalfertilizer.
l Use of green manure available inthe surroundings.
Fig 23: Green manure application
l Use of cow dung, poultry manure tosupplement chemical fertilizer.
l Use of rice husk charcoal.
Assignments1. Study materials available for IPNS in the area.
2. What are the strengths and weaknesses of IPNS presently done in the area.
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5. UPCOUNTRYINTERMEDIATE ZONE (IU)
Cropping systemsRice/potato/vegetable
Rice /vegetable /vegetable
Rice /vegetable
Rice /rice
Major crops are rice, potato, vegetable.
Available organic manuresources
Available organic materials are rice straw,paddy husks and green manure (Gliricidia;Wild sunflower, Ipil Ipil) and animal wastesuch as poultry manure.
Recommended fertilizerpractices
(See DOA fertilizer recommendation forrice)
Farmer practices of IPNS
Farmers add high amounts of poultrymanure and cattle manure for vegetableand potato crops. But they rarely useorganic or green manure for their rice crop.Since they use high amounts of TSP andMOP for vegetables or potato, such soilsare rich in available P and exchangeble K.
Suggestions to improve IPNSpractices
l Use of decomposed rice straw as asupplement to chemical fertilizer forpotato and vegetables.
l Use of organic manure as poultrymanure and cowdung for potato andvegetables.
Assignments1. List the organic materials available for IPNS for rice in the area.
2. Suggest ways of increasing the available materials for IPNS in rice in thearea.
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6. LOW COUNTRY WET ZONE(WL)
Cropping systems
There are several cropping systems
l Mawee lands - Rice / fallow
l Devaraddri - Rice / fallow
l Rice / Rice
Available organic manuresources
Available organic materials are rice straw,green manure (Gliricidia; Kekuna, Kaduru),rice husk, rice husk charcoal and animalwaste such as poultry manure,
Recommended FertilizerPractices
(See DOA fertilizer recommendation forrice)
Farmer practices of IPNS
l Use of NPK fertilizer
l Use of rice straw.
Suggestions to improve thepresent system of IPNS andFertilizer Use Efficiency (FUE)
l Straw recycling in addition torecommended levels of NPK.
l Poultry manure 3t/ha withrecommended levels of NPK.
l Additional levels of K to overcomeFe toxicity
l Cultivation of reduced iron tolerantvarieties such as BW 267-3 andLD-356 to escape Fe toxicity.
l Application of about 625 kg/ha ofcharred rice husk.
l More balanced nutrient management.
Fig. 24: Iron toxity in Rice in the low country wet zone
Assignments1. Study various organic materials used in the area for rice cultivation.
2. List the problems you observe for potential use of organic materials for IPNSin the area.
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Package of IPNS practices to obtain 200 bu/ac of rice in the dry &intermediate low country regions.
A) Fertilizer inputs to be used per ac (4000 m 2)
1. Organic manure
a) Rice straw - Entire quantity of the previous season rice crop butnot less than 3 tons
b) Cow dung - Dried cow dung 2 tonsorPoultry manure - Well rotted poultry manure 1 ton
c) Green manure - Tender loppings with leaves of (Gliricidia/Ipil Ipil/Karanda/Wal Sooriya/Sooriya etc.) 1 ton.
d) Rice husk charcoal - 250 kg of rice husk charcoal.
2. Chemical Fertilizersa) Urea 120 - 140 Kgb) TSP 45 - 50 Kgc) MOP 45 - 50 Kgd) Zinc sulphate 1 - 2 Kg
B) Time of application
1. Organic manureRice straw - After first ploughing
Green manureCow dung - After second ploughingRice husk charcoal
2. Chemical fertilizersBasal application 20 kg urea, 45-50kg TSP, 30 Kg MOP,1-2 Kg
Zinc Sulphate. Apply before levelling and incorporateinto the soil.
Top dressing. Apply urea, based on DOA recommendation orbased on colour of youngest leaf. (use leaf colourchart). Apply 20 Kg of MOP one before the last topdressings along with urea. Apply only urea at thelast top dressing.
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Section II
IPNS FOR VEGETABLES
This section deals with the generalimportance of cultivating vegetables inSri Lanka, vegetable growing eco-systems and cropping systems involvingvegetable crops, IPNS practices byfarmers and DOA fertilizerrecommendation, and the suggestionsand improvements to future IPNSprogrammes.
Following broad objectivesare to be achieved by theuser.1. To get knowledge on important
aspects of vegetables grown in SriLanka.
2. To know vegetable growing eco-systems and different croppingsystems.
3. To know the DOA fertilizerrecommendations, practices of IPNSby the farmers and suggestions toimprove present IPNS practices.
Introduction
l Vegetables are an importantcomponent of the Sri Lankan diet.
They provide
a. Minerals b. Vitaminsc. Fibre d. Energy
l Most vegetables grown in the countryare consumed locally, a smallpercentage is exported to countrieslike Maldives and the Middle East.
l The demand for vegetables is high,per capita consumption is far belowthe required standards of WHO.
l Vegetables have a horizontaldemand throughout the year but thesupplies are seasonal due to cropand location differences.
l This results in price fluctuations andless demand for certain high pricedvegetables during off seasons.
l Our production trends are very lowimproper fertilization and nutrientmanagement are reasons for yieldand income losses.
l Current demand for vegetable quality
Fig 25 Cabbage grown as a monocrop in UCWZ
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such as appearance, right size,colour, flavour and keeping quality isincreasing.
l Vegetables free from residues ofheavy metals and pesticides arepreferred and such vegetables fetchhigh prices.
l Over use of Nitrogeneous fertilizerswith high accumulation of NO
3-N in
tissues are also not advocated forhealth reasons.
l In Sri Lanka vegetables are broadlyclassified into local and exotic.
l Local vegetables are those endemicspecies or introduced from timeimmemorial, whereas exoticvegetables have been introducedrecently.
l A large number of local vegetableslike 'tibbatu', 'thalana batu' and'thumba karawila' have a highconsumer demand.
l Vegetables are grown under differentsystems of mono cropping andmixed cropping. The latter ispracticed when land is limited.
l Mixed cropping systems carry two tothree crops or even 6 to 7 crops.Often a relay system is found in manyplaces.
Vegetable growing eco-systems
l Exotic vegetables are extensivelygrown in the up country regions ofboth wet and intermediate zones.
l Exotic vegetables are grown undergood management practices and withsupplementary irrigation.
l Local vegetables are limited to themid country and low country regions.Their management levels are lowercompared to the level of the exoticvegetables. Supplementary irrigationis practiced in some areas but rainfedcultivation is very common.
l Intensive cultivation of localvegetables under selected crops isdone in different geographical areas.
l Gotukola is a special crop in theChilaw-Arachchikattuwa areas.Brinjal and 'Beeralu' radish isproduced extensively in the Mataraand Wariyapola areas. Tomato andOkra are grown in the Matale districtin the intermediate zone.
l Yams for using as vegetables arecommon in the Gampaha andKalutara districts.
Nutrient management invegetable production (Farmerpractices).
l Vegetable growers add more thanthe recommended rates of fertilizerand organic manure applications.This habit is universal.
l Farmers apply high doses offertilizers and sometimes foliarnutrient solutions though the latterhas not proved to be essential.
l Phosphorus fertilizers which arerecommended to be applied as abasal application are applied with topdressings which results in wastageand high build up of P in the soil.
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l Top dressed fertilizers are notcovered up by soil and losses occur.
l Some farmers apply organic manureas top dressings.
1. VEGETABLE BASEDCROPPING SYSTEMS OFTHE UP COUNTRY WETZONE (WU)
Recommended practices
l Vegetables are cultivated throughoutthe year either in rotation with potatoor otherwise.
l Addition of organic manure as wellrotted cow dung, poultry litter andchemical fertilizers arerecommended.
l Liming at 2t/ha every 1-2 years isrecommended. Lime should beadded 2-3 weeks before the additionof chemical fertilizers.
l Nutrients from organic manures usedshould be accounted for; this requiresthe adjustment of PK in the chemicalfertilizers used.
l Soil testing in every two years willenable the evaluation of the nutrientstatus of the soils.
l A starter dose of P and K fertilizersis necessary in spite of a heavy buildup of these nutrients in the soils.
l No P fertilizers should be added astop dressings.
l All N fertilizers should be coveredwith a layer of soil to preventvolatilization losses. Use only straightfertilizers.
General farmer practicesl Farmers do not allow the soil to rest
and only a short period is allowedfrom one crop to another.
l A few farmers transport soil fromelsewhere to be applied as top soil.The reason for this is not well known,but nematode build up, nutrient buildup and acidification of soils, may be
Fig 26: Intensive application of cowdung
some of the reasons.
l Farmers add large quantities oforganic manure to soil after liming.The rates vary from 20-60 t/ha. whichis too high.
l Liming is done with quick lime anddolomite. The former is used in lesserquantities but the latter sometimesexceeds recommended practices.Fields are not allowed more than afew days (3-4 day) after liming whichis not desirable
l Ammonia based fertilizer mixtureswhen added to limed soils liberateammonia gas, polluting theatmosphere.
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l Many farmers continue to usefertilizer mixtures. This results in theuse of phosphorus containingmixtures as top dressings.
l Most farmers apply liquid fertilizers2-5 times depending on the types ofcrops.
l Farmers seldom recycle crop residuedue to the fear of proliferation ofdisease organisms.
l Cropping systems follow a setpattern, which includes a crop ofpotato in the annual cycle. Radish isgrown during the wet windy seasonwith minimum addition of plantnutrients.
*Except Badulla district
2. VEGETABLE BASEDCROPPING SYSTEMS OFTHE UP COUNTRYINTERMEDIATE ZONE(IU)
Recommended practices
l Vegetable growing areas are of twotypes.
a. Vegetable-potato growing uplands.
b. Rice-potato-vegetable growing ricelands.
l Practices listed for the WU areapplicable.
l Poultry manure is recommended.Liming should be done according tothe type of crop grown. Potato scabis controlled at low pH while clubrootof cabbage is controlled at high pH.
l Poultry litter has the capacity tocorrect acidity.
l Combined use of chemical fertilizerswith poultry manure gives promisingresults (Table 8)
Table 7. Fertilizer recommendations for some vegetable crops
Crop Recommendation (kg/ha)N P
2O
5K
2O
Leek 200 125 90Capsicum 90 100 80Potato 150 125 150Tomato* 90 150 80Bean 100 125 90
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Table 8: Effect of organic manure andchemical fertilizers on cabbage yield.
3. VEGETABLE GROWINGSYSTEMS OF THE MIDCOUNTRY WET ANDINTERMEDIATE ZONES(WM & IM)
l Bulk of the traditional localvegetables are grown in this area.Many crops are grown rainfed bothin uplands and lowlands.
l On the uplands vegetable-vegetableor vegetable-fallow systems occurdepending on the availability ofrainfall.
l In rice based cropping systems amaha crop of rice is followed by ayala crop of vegetables.
l Both mono and mixed cropping iscarried out in rice based croppingsystems.
Recommended practices
l Use organic manure as cow dung,poultry litter and other availablesources.
l Lime the soil, if pH is low.
l Apply straight fertilizers based onsoil test recommendations.
l Recycle crop residues, if free fromdiseases.
General farmer practices
l Farmers who grow qualityvegetables apply organic manuresas cow dung, poultry litter or greenmanure. Some farmers mulch theircrops with straw of the previous ricecrop.
Manure application rate - 10 t/ha, chemicalferilizer application rate - DOArecommended level.
General farmer practices
l Farmers pay attention to thevegetable / potato crop in rice basedcropping systems than the rice crop.
l Organic manures are not used at thesame rate as the WU farmers.Poultry litter is often used by thetomato growers.
l Other practices are similar to that ofthe WU, except in crops like brinjal.
l Brinjal farmers seldom apply organicmanure, but farmers who haveapplied organic manure obtainedhigher yields.
Treatment Yield(t/ha)
Control 10.4
Chemical fertilizer 55.0
Cattle manure 32.4
Compost 33.8
Poultry manure 58.0
Cattle manure+Chemical fertilizer 55.3
Compost+Chemical fertilizer 57.9
Poultry manure+Chemicalfertilizer 88.1
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l Mixed cropping is practiced in bothtwining and erect types of crops.These types of crops are fertilizedat different times. As a result heavyapplication per unit area takes place.
l Most farmers rely only on chemicalfertilizers, some have got used tofoliar applications.
l Recycling of vegetable crop residuesis seldom carried out.
4. VEGETABLE GROWINGSYSTEMS OF THE LOWCOUNTRY DRY ANDINTERMEDIATE ZONES.
l Vegetable cultivators in the areaadopt both primitive and intensivemethods.
l Vegetable cultivation during themaha rainfed systems make use ofavailable plant nutrients of the soil,often a dose of urea is applied toboost growth.
l Vegetables are grown round the yearin the well-drained coastal regionsof Kalpitiya and Nilavelly areas or assemi-perennial leafy vegetables inthe Arachchikattuwa areas.
l An intensive form of vegetablecultivation has evolved around thelift-irrigated waters of the dug wellprogrammes. These are distributedin the dry and intermediate regionsof the Kurunegala, Puttalam, Mataleand Anuradhapura district.
l A rice based cropping system isfollowed in the dug-well programmewith rice being cultivated during themaha season.
l An unique feature of the intensivesystem of cultivation is the repetitionof the same crop two to three timeswithin the same season.
l Perennial crops of tibbatu, thumbaand mormodica varieties are grownon uplands with heavy applicationsof chemical fertilizers.
l Cooking bananas are grown with orwithout irrigation using chemicalfertilizers.
Recommended practices
l Use of organic manure as cow dung,goat dung, poultry litter, crop residuesand green manure.
l Soil and water testing for quality ofirrigation water of dug wells.
l Soil test based fertilizerrecommendations using straightfertilizers will keep balance of plantnutrients.
l Erosion control of soils to retain topsoil and mulching of soils to preventsalt movement upward.
l Recycling of crop residues and croprotation should be practiced.
l Farmers practice monocrop oftenfollowed by another crop of the samespecies.
l Organic manure is not added as ageneral practice but a handful offarmers obtain higher yields, usingorganic manure.
l Farmers attempt to rely on chemicalfertilizers and foliar applications.
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5. VEGETABLE GROWINGSYSTEMS OF THE LOWCOUNTRY WET ZONE(WL)
l Vegetables are grown in associationwith rice based cropping systems;either during the maha season onwell drained lands or on "ovita" ofthe rice lands.
l Vegetables are also grown on well-drained marshy lands and on uplandsadjoining streams.
l Erect and twining type local vegeta-bles and leafy vegetables are themain crops.
Recommended practices
l Draining of vegetable beds, erosionand flood control.
l Application of organic manure andchemical fertilizers after obtaining soiltest values.
Fig 27: Gotukola cultivation at Arachchikattuwa
l Use of green manure and cropresidues as mulches and a sourceof organic manure.
l Liming of soils to adjust pH whennecessary.
Farmer practices
l Farmers have specialized in theproduction of certain species inidentified locations. Brinjal and'beeralu' radish is grown in theMatara district.
l Here heavy application of organicmanure is done; sometimes as basaland top dressings.
l The leafy vegetables are heavilyfertilized both with organic manureand chemical fertilizers.
Assignments:1. Find out ways of obtaining organic materials by farmers in the area.
2. List organic materials available in the area for IPNS in vegetables.
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Section III
IPNS for Chilli, Onionand Maize
This chapter on chilli, onion and maizegives a general introduction to nutrientremoval, farmer practices, croppingsystems, current fertilizer recommenda-tions and suggested IPNS practicesusing available materials.
It is excepted to achievefollowing objectives.
1. To know general characteristicsof chilli, onion & maize.
2. To get information on croppingsystems adopted in different agroclimatical zones for these crops.
3. To impart knowledge on currentfertilizer recommendations andfarmer practices for these crops.
4. Suggestions for the adoption ofIPNS in chilli, onion & maize.
1. Chilli
Introduction:
l Chilli is a cash crop grown in SriLanka and is used as a condimentin the daily diet.
l Chilli is grown from sea level to 1600m above mean sea level. It is moreadaptable to the dry and intermediatezones of the low country dry zone.
l Chilli was traditionally grown as achena crop in the past. Severalvarieties are now systematicallycultivated as an irrigated mono cropboth in the well drained low landsand the irrigated uplands.
l It is grown as a rainfed upland cropduring the maha season.
l Chilli is an annual crop (120-150days) with a yield potential of 5t/ha(dry chilli) resulting in a heavyremoval of plant nutrients.
l It is grown in soils generally low inplant nutrients and organic matter.
l Chilli is grown for both green chilli(vegetable) and dry chilli.
Nutrient Removal
Table 9: Nutrient removal by Chilli crop yielding 2 t/ha
Element N P K Ca Mg S Total
Removal (kg/ha) 64 6 84 10 9 8 181
Source: Amarasiri and Perera
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CHILLI GROWINGENVIROMENTS ANDCROPPING SYSTEMS
The following chilli based cropping systemshave been identified.
1. Chilli-fallow system:Rainfed uplands.
l Low input system
l Soil moisture is the major productionconstraint.
l Low chemical fertilizer and otherinput use.
l Uncertain rainfall.
l Establishing crop with first rains.
l No basal fertilizer application.
l Top dressing of fertilizer may bepracticed depending on rain.
l Low application of organic materials.
2. Vegetable–Chilli system :Uplands with supplementaryIrrigation
l Under agro-wells farmers establishthe chilli crop in late August or earlySeptember to catch high prices forgreen chilli.
l High input system.
l Chemical fertilizers and pesticidesused heavily.
l No organic materials applied.
3. Fallow - Chilli system :Uplands and Lowlandswith irrigation.
l Establish chilli in December afterheavy rain to avoid high incidenceof pests & diseases due to excessiverains.
l Organic manure applications arerarely practiced.
4. Rice- Chilli system :Paddy fields underirrigation
l Major chilli growing system.
l Establish chilli crop after mahaseason’s paddy harvest.
l Well drained and moderately drainedsoils are used.
l High input system using heavy dosesof fertilizers and pesticides.
l Organic manures are rarely applied.
5. Chilli–Red onion System :Kalpitiya regosols
Fig 28: Chilli in Kalpitiya regosols
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l Fairly intensive chilli productionsystem.
l Soils are sandy regosols poor innutrients and water holding capacity.
l High rate of application of fertilizer& irrigation is common.
l Application of organic manure, covercrops and use of crop residues ispracticed by some farmers.
6. Green chilli – vegetablerelay cropping system:Kalpitiya regosols
l Conditions are the same as in chilliand red onion systems followed inKalpitiya.
l Chilli is grown for green pods mainly.
7. Chilli-Gingelly croppingsystem : Rainfed uplandsin Jaffna coastal belts andareas of Anuradhapura &Polonnaruwa.
l Chilli is planted to catch the maharains.
l Not an intensive system anddepends on rains.
l Crop residues of gingelly are used.
8. Chilli-Onion system inuplands in Vavuniya.
l Chilli crop grown in well drainedreddish brown earths.
l Organic manure application notcommonly practiced.
l Chemical fertilizers and liquidfertilizers are mainly used.
Farmer practices
l Practices of nutrient managementdiffer greatly from place to place.Farmers of the eastern coast keepcattle for a few nights on the land toenrich the soil with dung and urine.
l Farmers of Jafna, Kalpitiya and somein the Anuradhapura district addcattle manure before planting theircrops.
l Some farmers use poultry litter.
l Chemical fertilizers in the form ofmixtures are added as basal andtop dressings.
l Farmers who use straight fertilizersoften add urea as a top dressing butseldom cover it with soil.
l Foliar fertilizers are sprayed by mostfarmers.
Recommend fertilizer practices(DOA)
Fertilizer recommendations are given undertwo methods of chilli cultivation.
a. Irrigated cultivation
b. Rainfed cultivation
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Table 10 : Chilli (Irrigated & Rainfed)
Recommended usage oforganic materials
Depending on the availability of differentorganic materials, farmer can choosedifferent forms for chilli cultivation. Bothunder irrigated or rainfed conditions organicmatter application is beneficial.
1. Animal manure
These should be used 2-3 weeks beforeplanting by incorporating to the soil.
Materials used :
a. Cowdung 10-15 t/ha
b. Poultry manure 3-4 t/ha
c. Goat dung 5-6 t/ha
Depending on the conditions andavailability, application either individuallyor in combination can be done.
2. Mulching
l Depending on the availability ofmaterials such as rice straw,Gliricidia leaves, crop residues orother suitable materials mulches canbe placed in between rows instanding crops.
Fig 29: Mulching chilli with straw
Time of Application Irrigated Rainfed
Amount of Fertilizer (kg/ha) Amount of Fertilizer (kg/ha)Urea TSP MOP Urea TSP MOP
1. Basal dressing atplanting. - 100 50 - 100 50
2. Two weeks aftertransplanting (TD) 65 - 50 65 - 50
3. Four weeks aftertransplanting (TD) 85 - - 65 - -
4. 8 weeks aftertransplanting (TD) 85 - - 65 - -
5. 12 weeks aftertransplanting (TD) 85 - - 65 - -
Total 320 100 100 260 100 100
TD - top dressing
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l Rate : Generally 5-8 t/ha on drymatter basis up to a thickness of 2-4 cms above ground.
3. Crop Residues
l These could be ploughed in to thesoil. Even weeds can beincorporated.
l Ploughing immediately after harvestof the crop.
l Recycling the residue gives betterresults.
l Avoid planting the same crop afterincorporating crop residues fromidentical crops.
l Do not apply crop residues infectedwith pests & diseases.
4. Green Manure
Green manure crops can be grown duringthe fallow season if enough soil moistureis available. It can also be used as arotational crop. This can be ploughed inwhen 50% flowering has taken placed. eg.Sun hemp.
l About 30-40 kg/ha of seeds of agreen manure crop is required forestablishment.
l Green manure crops should beincorporated to the soil at least 3-4weeks before the establishment ofthe chilli crop.
l Green manure crops grown outsidesuch as gliricidia can be brought inand ploughed in at least 3-4 weeksbefore establishment of the chillicrop.
5. Compost
Compost can be prepared in the field andapplied before planting of the chilli crop.
Application is similar to that of cattlemanure.
l Compost at the rate of 5-10 t/ha issufficient.
l Crop residues can be compostedand used subsequently.
Assignments1. Study chilli based cropping systems in your area.
2. Identify and list different organic materials which can be used for IPNS inchilli cultivation.
3. Note different IPNS practices for chilli done by farmers and suggestimprovements.
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2. Red Onion
Introduction
l Red Onion is a condiment crop whichis an important part in the Sri Lankandiet.
l Red Onion is grown in different partsof the country for two purposes.
i. For bulb production.
ii. For spring onions.
l Bulb crops are important cash cropsfor the producers.
l Per capita requirement of red onionis 4-7 kg/yr and the presentproduction is enough only to provide2 kg/y per head.
l Red onion is grown as a monocropwhich fits into the following identifiedcropping systems.
RED ONION BASED CROPPINGSYSTEMS
1. Red onion cultivation inhilly areas : Ratnapuradistrict. (Ambewila,Sooriyakanda, Kolonnaarea)
l Grown in maha under rainfedconditions to fetch higher prices.
l Some soil conservation practices areadapted. Lands are prone to soilerosion.
l Chemical fertilizers are used.Organic manure usage is limited.
l Production is affected by fungaldiseases.
2. Red Onion – Red onionsystem: Trincomaleedistrict.
l Practiced in sandy soils in the Nilaveliarea.
l Continuous cultivation is practiceddue to better soil and climaticconditions.
l Fertilizer application is very frequentdue to sandy nature of soil.
l Mainly chemical fertilizers areapplied with little or no organicmanure.
3. Potato/Tobacco – RedOnion system : Jaffna.
l Very high income generating system,practiced under irrigation.
l High organic material application.Cowdung, green manure & cropresidues.
l Fertilizers are applied sufficiently.
l Crop establish in the yala season.
4. Rice–Red onion system :Ratnapura district.
l Red onions are grown underirrigation in paddy fields after maharice.
l Chemical fertilizers are used.
l No organic manure is applied.
5. Rice – Red onion : Jaffna.
l Similar to rice-big onion croppingsystem in the dry zone areas.
l Application of organic manure ishigh.
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l Planting done after maha rice crop.
6. Systems in sandyregosols: Kalpitiya
a Red Onion – Red onion system
b. Red Onion – Green chilli system
c. Red Onion – Vegetable – RedOnion system
d. Red Onion – Sweet potato – Red
Onion system.
l Red onion grows well in sandyregosols.
l Apply high fertilizer and frequentirrigation to compensate for quickleaching.
l Organic manure is used.
l Can be grown throughout the yearexcept in very wet months ofNovember and December.
l Liquid fertilizer is used.
l Red onion/Red onion systemexposes crops to disease problems.
7. Red onion – Vegetable/OFC system: Telulla,Moneragala.
l Red onion crop is establish in yala.
l Maha crops are vegetables / OFC.
l Chemical fertilizer is used sufficiently.
l Organic manure usage is low.
Proven IPNS practices used byfarmers.
l Soils are prepared to seed the bulbsby keeping cattle on the land or
applying large quantities of organicmanures like cowdung/poultry litter,specially by the Nilavelly farmers.Few farmers apply green manure.
l Seed bulbs are planted at a closespacing on the sand.
l Often two irrigations are given daily.6-8 applications of chemical fertilizermixtures are carried out.
l Cultivation of onions on raised bedsis carried out in most of the othergrowing areas.
l Irrigation is done :
By filling the furrow
Sprinkling water
Use of sprinklers
Drip irrigation systems
l Two to three fertilizer applicationsare carried out.
l Few farmers practice the use ofadding organic manure beforeplanting seed bulbs. Farmers whodo it get better yields.
Fig 30: Red onion grown in regosols
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l Farmers seldom mix appliedfertilizers with the soil, they presumethat fertilizers will dissolve in theirrigated water and will be used bythe crop.
l Farmers cultivate hilly slopes evenup to 45% in the Sooriyakanda arearesulting in severe soil erosion.
Recommended practices
l Application of organic manuresbefore planting into the holes.
Animal wastes – Farm yardmanure, dried cowdung,poultry litter, goat dung etc.
Green manure of sunhemp,gliricidia, thespesia etc.
Crop residues of green gram,black gram, cowpea.
l Mulching of beds with rice straw,rice husk and other crop residuesafter planting.
l Application of chemical fertilizersand incorporating into the soil.
l Application of ammonium sulphateas basal fertilizer for sandy coastalsoils. Top dressing with NK fertilizers.
l Limit over irrigation.
3. Big Onion
Introduction
l It is a condiment crop which is anessential ingredient of the daily dietof Sri Lankans.
l Total annual requirement is 90,000tons of which 50% is importeddespite the possibility of producingit locally.
l Area under cultivation is 3000 haproducing about 22500 tons.
l Potential yield is about 30 t/hhowever average yield is 10 -12t/h.
l Big onions are mostly grown in thecentral parts of the island on welldrained RBE/LHG soils. It is grownas a yala crop in paddy soils as wellas in uplands using irrigation watersupplied through reservoirs or thatis lift irrigated from dug wells ordrainage channels.
l Farmers growing big onions raisedfrom seedlings on beds with little orno addition of plant nutrients.
l Seedlings are planted on raisedbeds.
l Some farmers use organic manuresbefore planting the seedlings. Manyrely on chemical fertilizers only.
l A close spacing followed by overapplications of NK fertilizers as atop dressing is practiced.
l Often farmers try to correct theimbalanced application of nutrientsbrought about by overuse of fertilizerby spraying foliar nutrients.
BIG ONION - BASEDCROPPING SYSTEMS
1. Rice – Big onion system :Lowland paddy fields lowcountry dry zone
l Comparatively high input system.
l Big onion is grown during the yalaseason after the maha season riceat the end of April rains.
l Low application of organic manure.
l Chemical fertilizer and liquid fertilizerare applied frequently.
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l Heavy use of fungicides &insecticides.
l Rice straw is available as a cropresidue.
2. Vegetable / OFC – BigOnion System : Uplandsof low country dry zone(DL)
l Mostly practiced under agro-wells.
l Big onions are planted after theprevious season vegetables such aslong bean, okra, brinjal and OFClike maize, chilli, cowpea, soybean,black gram & finger millets.
l Establishment of onions a few weeksearlier than the first cropping systemto catch higher prices.
l Use of organic manure is very low.
l Use comparatively high doses offertilizer & pesticides.
RECOMMENDED PRACTICES
l Are similar to that of the red onioncrop.
l Poor quality irrigation watercontaining dissolved salts canreduce yields.
l Fertilizers should be applied to meetthe yield targets.
l Over application of N fertilizersresults in bulbs with very poorkeeping quality.
l Conservation methods to prevent theloss of top soils in uplands arenecessary.
l Recycling of crop wastes should bepracticed.
l Crop rotation to control pathogenbuild up is necessary.
Fig 31: Sunhemp grown for green manuring of onion
Assignments:1. Study onion based cropping systems in your area
2. Identify and list different organic materials that can be used in IPNS for onioncultivation.
3. List diffrent IPNS practices done by farmers and suggest improvmentsfor onion.
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4. Maize
Introduction
l Up to recent times maize was grownas a chena crop mixed with othercereals, legumes and other crops.
l At present it is grown as a monocropwith varying densities to give50000 –60000 plants / ha.
l Maize is grown both as a rainfedmaha crop and as an irrigated yalacrop in the well drained paddy landsand uplands with supplementaryirrigation.
l Farmers do not pay enough attentionto balanced fertilization in growingmaize. Under heavy densities ofplanting N fertilizers are used heavilyon soils already depleted in organiccarbon, P and K.
l Crop residues are seldom recycledand are often burnt, resulting infurther depletion of soil carbon andloss of plant nutrients.
l Close planting with two to threeseeds per hole results in only oneplant growing fully and the othersweakening to give small sized cobs.
Recommended practices
l Maize is a heavy remover of plantnutrients and the roots go deep upto 2m in loose soils. Thus adequateplant nutrients are necessary toobtain a crop yield of 6-8 t/ha.
l Basal application of fertilizers andmixing them with the soil arenecessary.
l Application of organic manure, isbeneficial.
l Crop residues as stover and cobstalks can be composted and appliedto the next crop.
l Over use of N should be avoided.
l N deficiency results in a loosely filledcob, while potassium deficiencyresults in empty cob ends.Phosphorus deficiency results inshrunken grains. (See appendix 1a)
l A balanced fertilizer managementshould be followed. Heavy yieldingvarieties should be compensated byadding more plant nutrients.
Fig 32: Maize
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Assignments1. Describe how maize crop residues can be used in your area.
2. Indicate different maize based cropping systems in your area.
l Maize could be grown mixed withlegumes such as ground nut, greengram or cowpea. This increases theland utility index.
l Farmers cultivating maize underrainfed cultivation must plant seedsalong with the first rains. This willbenefit the roots to capture thenitrates formed with bacterial action.Delay in planting results in the lossof these nitrates through leachingand denitrification.
l Maize roots are susceptible to poordrainage, which results in stuntedand yellowing of leaves. Also waterstagnation results in loss of Nthrough denitrification of the soil Nand any added N fertilizers.Adequate drainage should beprovided. Top dressing of fertilizershould be done after the soils havebeen drained.
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Section IV
IPNS PRACTICES FORFRUIT CROPS
This section deals with banana, papaw,pineapple, passionfruit, citrus, rambutanand mango which are important fruitcrops grown in Sri Lanka.
The following are the broadobjectives
1. To provide knowledge onphysiological and nutritionalcharacteristics of fruit crops.
2. To give information on currentnutrient management practices offarmers and DOA recommenda-tions.
3. To suggest IPNS that can beadopted for fruit crops.
Introduction to Fruit CropsNature and Characteristics
The physiology and nutrition of fruit cropsare different from annual crops in manyrespects. Some of the aspects which needconsideration are
lllll Long vegetative phase (most of themare perenials)
lllll Large tree size
lllll Long life span
lllll Very high bio-mass
l Very low proportion of economicalyield to total bio-mass at fruiting
e.g.
Banana 5 - 10%
Papaya 4 - 6%
Pineapple 50 - 60%
Passion fruit 5 - 10%
Lime 5 - 7%
lllll Very high non-productive biomass.eg. branches, wood, trunk etc. thathad to be maintained.
lllll Very high food deposits in non-edibleportions of the tree. eg., bark, woodetc.
lllll Large canopy with its yearly newflush.
lllll Very high maintenance of respirationof the tree.
lllll Yield is sensitive to weather, climateand nutrition.
lllll Balanced nutrition, time of applicationand soil conditions are critical factorsthat affect the final yield.
lllll Flowering, fruit yield (number of fruitsand fruit size) and fruit quality (sugarand acid content, firmness, shapeetc.) are governed by amount, typeand availability of primary and micronutrients.
lllll Amount, type, availability andsolubility of nutrients in the soil alsoaffect alternate bearing and fruit/flower abscission.
lllll Plant nutrient removal alone is not areliable measure to determine thenutrient requirement for most fruitcrops.
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Therefore, selection of proper fertilizermaterials, appropriate time of application,suitable method of application and correctamounts are extremely important to obtaina good yield.
1. BANANA
lllll Extent cultivated: about 49,000 ha.which contributes to 46%of the totalfruit crop extent in the island. (1997)
lllll Varieties and distribution:
lllll For banana under coconut, farmersuse a layer of coconut husks in thebottom of the planting hole and acoir dust layer as a mulch to maintainmoisture levels.
lllll However, organic manureapplication is not a common practiceamong farmers in Sri Lanka.
Top dressing
lllll No organic manure is applied ineither commercial or homegardencultivations.
lllll Most of homegardeners do not useany chemical fertilizer for theirbanana crops.
lllll Large-scale growers apply bananafertilizer mixtures available in theopen market at about 1 kg/clump/year with 2-spilt applications /year.However, gradually they are movingtowards DOA recommendations.They very rarely use organic manure.
Fig. 33: Pineapple intercrop with banana
Current nutrient managementpractices
1. Farmer practices
Basal dressing
lllll Compost, about 5kg/planting hole.(kitchen waste, cattle manure orfarmyard manure are also used).
lllll Poultry manure is not used forbanana, as farmers believe that itpromotes banana diseases.
Agroclimatic VarietiesZone recommended
Dry Zone Kolikuttu, Ambul, Seeni, Ash,Mondan varieties, Atamuru
Intermediate Kolikuttu, Ambul, Seeni,Zone Anamalu, Ambon, Ash,
Mondan varieties,Atamuru, Kitala
Wet Zone Ambul, Ambon, Puwalu,Seeni, Anamalu, Rathambala,Suwandel, Bin kesel,Mondan varieties, Atamuru,
Kitala
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l Some farmers use other fertilizermixtures such as coconut mixtures,paddy mixtures etc. about 1 kg/clump/year with 2 equal splits.
l Time of fertilizer application andfrequency depend on rain andeconomic condition of the farmer.However, commercial growers applyfertilizer three times a year withirrigation.
Mulching of banana clumps
l After the first top dressing application,some farmers use various mulchingmaterials for banana (straw, coir-dust, saw dust, paddy husk, bananaresidues etc.) in order to reducewater evaporation from the soilsurface and thereby maintainoptimum soil moisture level.However, banana residues are notfound to be a good material as amulch due to pest infestation.
2. DOA recommendation
Basal dressing
Organic manure
l Compost or cattle manure at the rate2-4 baskets/ planting hole beforeplanting and also as top dressingonce a year. (Spread over the surfacearound the clump and incorporateinto the soil together withrecommended chemical fertilizer).
l Wood ash whenever available.
Chemical fertilizer at planting
l No chemical fertilizer isrecommended at planting as a basaldressing.
l Kieserite/ Magnesium Sulphate(Epsom salt) at the rate of 450g/ orDolomite 600g/ planting hole for wetzone soils once in 2-3 years.
Fig. 34: Banana -mulching with banana clumps & leaves
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Time of fertilizer application
lllll First application : 2months after planting
lllll Second application : 4months after first application
lllll Fertilizer application should be doneat 4 month intervals. This method issuitable for irrigated banana wheresoil moisture level can be easilymaintained.
lllll For rainfed cultivation, 675g/ clumpof the relevant fertilizer mixture isrecommended at the onset of yalaand maha rains. However, it isadvisable to split the fertilizer amountin to 3 parts and apply 3 times a yearwhenever possible.
Disadvantages of currentfarmer practices
lllll Current farmer practices do not suitsustainable production of banana.They rarely use both organic andchemical fertilizers. However, plantremoves nutrients from the soil foryield and other biological masses.Since these are not recycled withinthe system, the soil becomes
Table 11: Top dressing fertilizer mixture
unproductive with time. Further,intercropping banana with othercrops lead to erosion of the soil. Theresult will be a degraded soil, whichdoes not lead to sustainable bananaproduction.
lllll Therefore, an Integrated PlantNutrition System (IPNS) is moreuseful for fruit crops like banana.
Suggested IPNS programme forbanana
Basal application
lllll Any kind of green manure, animalwaste (solid/liquid), kitchen waste,crop residues or even high C/N ratiomaterials such as coir dust/saw dust/ rice husks can be used as a basalorganic material/ amendment forbanana. If materials used have ahigh C/N ratio, it is advisable to mixthem with low C/N ratio materialssuch as poultry, cattle manure etc. toachieve quick decomposition insitu.Banana trunks after harvestingshould be composted before applyingas an organic amendment.
Fertilizer Wet zone Dry & intermediate zonetypes amt.(g) amt. (g)
Urea 110 120
Rock phosphate 150 -
Triple superphosphate - 80
Muriate of potash 190 250
Total per clump 450 450
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lllll If poultry manure is used, mix withsoil in the planting hole and allow toremain for a week to moisten beforeplanting is done.
Top dressing
lllll Banana is a shallow rooted crop(45-60cm). Therefore, application ofany kind of easily decomposableorganic manure as a top dressing at3 months interval is highly beneficial.
lllll For this purpose, cattle manure, FYM(solid/liquid), compost, greenmanure, poultry manure, goatmanure and other animal wastecould be used.
Amount of manure (dry basis)kg/clumpPoultry manure 3-5Cattle and other animal
manure 5-10Green manure 7-10
Method and time of application
lllll Spread the organic material about30cm away from the clump base butwithin one meter around the clumpand lightly mix with the soil.
lllll Application at 4 month intervals alongwith recommended chemical fertilizeris suitable and economical.
lllll If the plantation is free of pests anddiseases, chopped trunks/leaves ofharvested banana plants can be usedas a basal organic material for newplanting holes after treatment with asuitable pesticide and allowing it todecompose in-situ. This will help torecycle the nutrients. This cropresidue can be easily decomposedby mixing with cattle or poultrymanure.
lllll Banana crop residue can also beused as a mulching material aroundand between clumps after choppingthem, if banana pests and diseasesare not present. This practice willconserve moisture.
lllll Since animal manure promotesbanana pests especially bananaweevils it is important to takeprecautions against them. Apply 10gof carbofuran into each planting holebefore planting.
Assignments:1. Study IPNS adopted in your area for banana.
2. List materials that are available in your area which can be used for IPNS.
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2. PAPAYA
Extent cultivated : 2700 ha. (1995)
Varieties and distribution
Very few varieties have been identified forcultivation in Sri Lanka, as most varietiesare susceptible to viral diseases in the wetzone.Agroclimatic RecommendedZone varietyWet zone Local selections
Dry zone Ratne, Local selections,Solo Hawaii, Solo sunrise
lllll Papaya is a heavy feeder of plantnutrients and it is a fast grower anda heavy bearer. It bears fruitsthroughout the year with a peakfruiting season in May-July.
Current nutrient managementpractices
Farmer practices:
lllll Most farmers use cattle manure or
compost before planting, at the rateof about 1-2 baskets/planting hole.
lllll A coconut husk layer is used whenintercropping with coconut.
lllll No top dressing application of organicmanure is practiced.
lllll Farmers do not follow the DOArecommendation of chemicalfertilizers. Commercial growers usestraight fertilizers as recommendedby the DOA, but they add fertilizermore frequently than therecommendation. They also applycattle manure as top dressing morefrequently. This leads to over use offertilizer and manure, resulting inmore succulent and virus susceptibletrees. Also, application of manureclose to base of the plant may causecollar rot disease.
lllll Some commercial growers usefertilizers with drip irrigation systems(fertigation). However, amount, typeand time of application are yet to beworked out.
Table 12: DOA recommendation (g/plant)
Agroclimatic Time of application Urea TSP Rock Muriate of Zone Phosphate potash
Wet Zone At planting 55 -- 80 952 months after planting 55 -- 80 95After every 3 monthinterval 55 -- 80 95
Dry & IntermediateZones At planting 60 40 -- 130
2 months after planting 60 40 -- 1306 months after planting 60 40 -- 130After every 3 monthinterval 60 40 -- 130
TSP = triple super phosphate
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lllll Despite papaya being a heavyfeeder, foliar nutrient application isnot yet recommended. Cattle manureat the rate of 5 – 10 kg/plant as basaldressing is recommended.
lllll Micronutrients so far have not beenrecommended though there aresome reports on suspecteddeficiencies. However, in some areasbumpy fruit disorder occurs which issuspected to be due to borondeficiency. For such areas, sprayingof 2% solution of sodium borate(borax) to foliage and fruits once in2 weeks or soil application at 10g/plant at the time of fertilizerapplication is found to be beneficial.
lllll Since papaya is a heavy feeder,proper nutrient management isneeded for sustainable production.Since nutrient removal as yield andbotanical mass is high and recyclingof nutrients is low in papaya orchards,a frequent application of organicmanure to the soil is very beneficial.
Suggested IPNS programme forpapaya
Basal
lllll Follow fertilizer programmerecommended by the DOA.
lllll Add 5-10 kg of cattle manure or4 -5 kg of poultry manure/plantinghole as a basal dressing 2 weeksprior to planting.
lllll Add chemical fertilizers as a basaldressing one week before plantingas recommended by DOA.
lllll Dolomite application before plantingat the rate of 5kg/ plant leads tochange of soil pH which enhancesavailability of plant nutrients.
lllll Add compost (5-10kg) / cattlemanure (5-10kg)/ poultry manure(4-5kg) every 3-4 months as a topdressing around the plant andincorporate into the soil. Thismanuring can be done along withchemical fertilizers and irrigationshould follow.
Fig.35: Control weeds and use it for mulching
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lllll Spray a 2% foliar nutrient solutionwhich contains boron, at least oncea month when the crop is 4 monthsold.
lllll Mulching the plants with straw, cropresidues, any type of animal manureor even live mulch of short age cropslike bush bean provides benefits togrowing papaya trees.
lllll In general, application of ampleamounts of compost and cattlemanure or poultry manure to the soilas basal adressing and as topdressings would be highly beneficial.
Assignments:1. Study actual situation of papaya growing in your area.
2. List various ways of using IPNS for papaya in your area.
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3. PINEAPPLE
Extent cultivated: 6000 ha. (1995).
Varieties and recommended areas :
Varieties: Kew
Mauritius
lllll Practically both varieties can begrown in areas that are suitable forpineapple cultivation. Generally Kewis widely grown in Badulla andMoneragala districts and Mauritiusin Gampaha, Kurunegala, Kegalle,Puttalam and Kalutara districts.
Current nutrient managementpractices
lllll Pineapple does not demand a richsoil. However, it responds well toadded fertilizer under mildly acidicsoil conditions.
Farmer practices
lllll Pineapple growers do not growpineapple twice in the same field asthey believe that after growingpineapple the soil is very muchdepleted of nutrients.
lllll Farmers generally do not use manureor chemical fertilizers as basaldressings.
lllll However, most farmers follow theDOA recommendation from 2 monthsafter planting.
lllll They use coir dust as mulch alongplanting rows 6 months after plantingto avoid moisture stress during flowerinitiating stage. However, coir dust isbecoming a scarce material andtherefore an alternative substitutehas to be found.
Fig. 36: Coir dust mulch application in pineapple
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lllll Some farmers use cadjan leaves asmulch along planting rows. However,pineapple growers do not applyorganic manure.
lllll Recommended chemical fertilizersare applied 2 months after plantingalong the planting rows andincorporated into the soil. Aftersecond top dressing, the coir dust isapplied as mulch. After coir dustmulching, it is difficult to continuefertilizing and therefore farmersbroadcast fertilizers around the plantbase which damages leaves.
lllll Soon after harvesting the main crop,the ratoon crop is fertilized in thesame way as the main crop.
DOA recommendation
This recommendation is applicableonly for wet zone.
Basal application
lllll No basal application isrecommended.
Top dressing
lllll 1 month after planting (g/plant):
Urea 10
Rock phosphate 10
Muriate of potash 15
lllll At 3-4 monthly intervals repeatapplication of this mixture.
IPNS programme for pineapple
lllll Pineapple soils are heavily depletedof plant nutrients as the removal isvery high (About 60% of the totalbiomass as economical yield).
lllll Amount of biomass that can berecycled during a 4-year crop is low.
lllll Soil erosion is comparatively high inpineapple growing soils.
lllll Since pineapple has a shallow rootsystem, most of the applied nutrientsare leached out.
lllll As organic matter application is notpracticed for pineapple, retention ofplant nutrients is low in the soil. Asa result, soil becomes infertile.
lllll Therefore, in order to maintain goodsoil physical, chemical and biologicalproperties, an IPNS programmeshould be adopted.
Suggested IPNS programme forpineapple
lllll A suitable and freely availableorganic amendment must be appliedas a basal dressing into the plantingfurrows. Eg. Plant residues or animalwaste.
lllll If coir dust is not available, use analternative material for mulching toreduce evaporation especially, duringflowering stage. Well-rotten saw dust,rice husk, cadjan leaves, bananatrunk chops straw or any othercomposted material can be used.
lllll Mealy bug control should beeffectively carried out before applyingany mulch.
lllll Crop residues from the previouspineapple crop could be compostedand utilized for the next crop.
lllll Heap soil at the plant base after everyapplication of fertilizer so that itbehaves as a soil mulch.
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lllll Apply about 2-5 t/ha of dolomite limeas it provides Ca and Mg, as a basaldressing to avoid browning andinternal breakdown of the fruit flesh.
lllll Foliar application of liquid fertilizerduring dry periods is much beneficial,
as soil application of nutrients isinefficient. Also, foliar application iseasier than soil application especiallyduring latter part of the growingseason when ground cover is high.
Assignments :1. If you are working in a pineapple growing area study the various practices of
IPNS adapted in the area.
2. List organic materials available in the area that can be used in IPNS.
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4. PASSION FRUIT
lllll Extent cultivated : 40 ha. (1997).
lllll Varieties and distribution:
Yellow variety : For dry zone
Purple hybrid : For wet andintermediate zone
Mani : For wet zone
Current nutrient managementpractices
Farmer practices
lllll Generally, compost or cattle manureis applied (about 10kg/ planting hole)before planting.
Table 13: DOA recommendation (g/plant)
lllll Recommended straight chemicalfertilizers are also applied as a basaldressing.
lllll Organic manure application as topdressing and mulching are notcommon practices.
Agric.zone Time Urea Rock phosphate TSP MOP Kieserite
Wet Basal 60 115 - 55 60
Zone 2 WAP 60 115 - 55 --
6 WAP 60 115 - 55 --
Thereafter at 6
monthly intervals
(second year) 115 230 - 105 --
3rd year 180 340 - 160 --
4th year 235 455 - 210 --
Dry &
Intermediate Basal 70 -- 105 50 --
Zones 2 MAP 70 -- 105 50 --
6 MAP 70 -- 105 50 --
Thereafter at 6
monthly intervals
(second year) 140 -- 205 105 --
3rd year 205 - 310 160 --
4th year 275 -- 415 210 --
WAP- weeks after planting, MAP- Months after planting
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lllll Viral diseases are the most limitingfactor for production of passion fruit.Use of organic manure or compostcan ameliorate the yield losses dueto this problem.
lllll Also, growth retardation due to viraldiseases can be suppressed byfrequent application of ampleamounts of organic manure orcompost.
lllll Soil moisture conservation is a mustfor passion fruit cultivation in orderto maintain the quality and quantityof fruit juice.
lllll Since recycling of residues of thiscrop is insufficient, organic manureshould be supplied in addition to meetthe demand.
lllll Passion fruit crop residues can beused as an organic manure and asa mulch.
lllll The soils are subjected to erosionleading to nutrient depletion.
Suggested IPNS programme forpassion fruit
lllll Application of cattle (5-10kg/pit) orpoultry manure (3-4 kg/pit) as basal,together with recommendedchemical fertilizers.
lllll Top dressing with cattle or poultrymanure (same rates as basal)together with recommendedchemical fertilizers and incorporationwith soil.
lllll Mulching with coir dust, straw orsuitable composted material.
lllll Foliar feeding of suitablemicronutrient solutions with highpercentage of potassium at floweringstage has a major advantage on thefinal fruit yield.
Assignments :1. Study IPNS practices adapted for passion fruit in the area.
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5. CITRUS (Lime and SweetOrange)
lllll Extent of cultivation : About 6000 ha.(1995).
lllll Varieties and distribution:
Lime
Local lime selections are mainly grown inthe dry and intermediate zones whereas inthe wet zone it is a common crop in homegardens.
Sweet orange - Bibile Sweet,Bibile Sweet seedless
Nutrient management practices
Farmer practices
lllll Cattle manure, kitchen waste, woodash, coconut husks and compost areused as basal applications.
lllll DOA fertilizer recommendation israrely used.
lllll Fertilizer application depends onsocio-economic factors and wateravailability in the growing area.
lllll Inconsistent price for the product isthe major drawback for citruscultivation in Sri Lanka and hencegrowers do not attempt to invest toomuch in it. As a result, fertilizer isused at a reduced level.
lllll Moisture stress during the fruitingperiod must be minimized in order toobtain a good yield. Therefore,application of organic amendmentsas basal and topdressings and alsoas a mulch, promotes soil moistureconservation and high yields.
DOA recommendation
Table 14: DOA recommendation for Lime and Sweet Orange (g/plant)
Agroclimatic Zone Time Urea TSP RP MOP
Wet zone Basal 75 -- 120 25Until bearing withincrements of 75 -- 120 25Up to maximum 2 splits/year 445 -- 730 160Bearing plants 2 splits/year 355 -- 680 320
Dry & Intermediate Basal 80 100 -- 45zones Until bearing, top dress with 80 100 -- 45
Up to (with 2 splits/year) 475 590 -- 270Bearing trees (2 splits/year) 270 620 -- 455
TSP - Triple super phosphate, RP - Rock phosphate, MOP - Muriate of potash
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lllll Since organic manure and fertilizerapplication as well as moistureconservation measures areneglected by farmers, sustainablecitrus yields are not achieved.
lllll Most of citrus growing soils do nothave sufficient moisture levelsthroughout the year and therefore,moisture conservation measures areextremely important.
lllll Since citrus crops are verysusceptible to micronutrientdeficiencies, such as zinc and iron,major emphasis should be given toapplication of these nutrients as foliarfeed at the correct time. At the timeof moisture stress, foliar feeding ofsoluble major and micronutrient isessential.
lllll Since citrus crops give only marginalreturns, farmers tend tointercrop them with othercash crops which leadto further decline of soilnutrient status.
lllll Nutrient deficiencysymptoms are verycommon in lime treesthat are grown indepleted soils. Thisleads to production oflow fruit yield of poorquality. Therefore, it isvery important to givemajor emphasis onnutrient management.This is easilyapproached through aproper IPNS.
Suggested IPNS programme forCitrus
lllll Apply compost (10-15kg) or cattlemanure (5-6kg) or poultry manure(3-4 kg)/ planting hole as a basaldressing.
lllll Any other organic amendment likeanimal waste can also be used.
lllll Follow the basal chemical fertilizerrecommended by DOA one weekprior to planting.
lllll Locally available organic manure canalso be used as top dressings oncein 6 months which should beincorporated into the soil.
Fig. 37: Mulching of Citrus plants
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lllll Follow the chemical fertilizerrecommendation for top dressingwhen there is sufficient moisture inthe soil.
lllll Maintain a mulch around the base ofthe plant, with materials such as ricestraw, crop residues or any othersuitable material.
lllll Spray foliar fertilizer especially duringdrought periods and also whennutrient defiency symptoms appear.
lllll Apply dolomite or kieserite asrecommended by DOA.
lllll Practice irrigation whenever possible.
Assignments :1. Study present practices of IPNS adopted in the area.
2. Give constraints and possibilities of using suggested IPNS programmesin your area.
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6. RAMBUTAN
Extent cultivated : 825 ha. (1995)
Varieties and distribution
Few varieties have been recommended,but many varieties and strains exist.
Malwana special
Malayan Red
Malayan Yellow
Rambutan is extensively grown inGampaha, Kalutara, Colombo, Ratnapura,Galle, Kegalle and Kandy districts.Rambutan needs lot of nutrients since it isa heavy bearer and an evergreen crop.
Organic matter is extensively used inRambutan orchards.
Nutrient management practices
Farmer practices
Organic manure
lllll Most of farmers add compost,Compost – 2-3 kg. for a pit of 1 x 1x 1m about 02 weeks beforeplanting.
lllll Young plants are mulched with straw,plant trash or any organic material.
lllll Bearing trees are provided with10-15 kg of compost twice a year.
Chemical fertilizer
lllll Basal dressing is applied 2-3 daysbefore planting.
Table 15: DOA fertilizer recommendations (application per plant)
Time of applicaion Urea (g) Rock Phospate (g) MOP (g) Total(g)
1. Basal 120 115 110 345
2. 6 months after planting 60 115 55 220
3. 1 year 60 115 55 225
4. 2 years 180 345 165 690
5. 3 years 300 575 275 1150
6. Every 6 months thereafter 360 690 330 1380
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lllll Top dressing frequency is as statedabove. Apply fertilizer over the areawhere canopy spread is projected.
lllll Incorporate into the soil.
lllll Apply top dressing soon afterharvesting or end of the fruit season.Split the first dose into two an applyone part each season.
lllll Do not apply chemical fertilizerduring dry spells. Also, do not applyduring rainy spells.
lllll Apply 2250 g of dolomite per treeper year, two weeks before chemicalfertilizer is added. Incorporate intothe soil.
lllll Apply organic manure to the treesliberally in addition to chemicalfertilizers.
Suggested IPNS programmefor Rambutanlllll Add 10-15 kg of cattle manure or 4-
5 kg of poultry manure into plantingpit at least two weeks beforeplanting.
lllll Dolomite (5kg / pit) as basal dressing
lllll Follow the fertilizer programmerecommended by the DOA.
lllll Basal fertilizer + top dressing.
lllll Add compost 10-20 kg, or cattlemanure 15-20 kg or poultry manure5-10 kg per tree every 3-4 monthsas top dressing around the trees,and incorporate into the soil. Thismanuring could be done along withchemical fertilizers. Irrigation shouldbe done when possible.
lllll Mulching is a must to maintain soilmoisture.
Seedling /Root stock plantproduction
Temporary Iron deficiency is a generalproblem in young Rambutan seedlings.Yellowing of interveinal area of leaves thatleads to chlorosis of entire leaf is suspectedto be due to iron deficiency or unavailabilityof iron in the rooting medium or inability ofthe seedling to absorb the nutrient. In thisregard, spraying of Ferrous sulphate (2%)will ease the problem.
Usual potting mixture is cattle manure, topsoil and sand mixed in equal amounts.(well rotted cattle manure is very suitable).Potting mixture may be enriched withKeiserite or dolomite powder. Applicationrates should be decided accordingly.However, suggested rate is 3-4 kg ofdolomite or 2-3 kg Keiserite per 100 cubicfeet of potting mixture. 8-10 g of dolomiteor 6-7 g of Keiserite per pot may be added.Potting medium should be kept under fieldcapacity, always.
Assignments :1. Study present practices of IPNS adopted in the area for Rambutan.
2. Give constraints and possibilities of using suggested IPNS programmesin your area.
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7. MANGO
Extent cultivated: 12160 ha. (995).
Varieties and distribution
Large number of varieties are cultivated allover the island.
Mango is commonly found in almost alldistricts except in the Nuwara Eliya district.Mango population in the island has beenpropagated through seedlings. Owing tothat, the trees are heterogenous in size,yield quality and other characteristics. Theyare huge trees producing a large quantityof fruits. However, they are generallyirregular or alternate bearers. Heavy yieldsare obtained usually once in few years.
Mango trees need a large quantity ofnutrients to maintain the tree itself. Inaddition to that, they need more nutrientsbecause nutrient removal through fruits isvery high.
Nutrient management practices
Farmer practices
Basal drssing
1. Organic manure
lllll Most farmers add ample amounts ofcompost into the planting pit one totwo weeks before planting.
lllll One third of the potting mixture formango plants, consists of cattlemanure or compost.
2. Chemical fertilizer
lllll No chemical fertilizer is added asbasal dressing for mango plants atplanting. However, chemicalfertilizers are added to the plantingpit by commercial growers. Theyfollow the departmentalrecommendation.
Top dressing
i. Organic manure
Generally no top dressing of organicmanure is used for mango bygrowers. However, mulching thetrees with organic matter such asstraw, plant residues etc. is acommon practice in the dry zone.
Dry Zone Intermediate Zone Wet Zone
Karatha Colomban Karatha Colomban Vellai ColombanVellai Colomban Vellai Colomban Peter passandWillard Peter passand Gira ambaKohu amba Willard Dil passandAmbalavi Betti amba
Kohu amba
Malwana
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ii. Chemical fertilizer
Farmers do not apply any fertilizer to mangotrees except in few home gardens in thewet zone.
Commercial growers apply chemicalfertilizers to mango trees as recommendedby the Department of Agriculture. They donot use foliar nutrient sprays on mango.
Suggested IPNS programme formango
1. Add 10-15 kg. of cattle manure /compost in every season at the onsetof seasonal rains or two weeks beforeapplication of chemical fertilizers.
lllll Follow the fertilizer programmerecommended by the DOA
lllll Mulching is a must to maintain soilmoisture during fruit set and fruitgrowth. Mango flowers in dry spells.Fruit grows properly under goodlevels of soil moisture. Otherwise fruitabscission can occur. Therefore,mulching after flowering is moreimportant. Apply mulch during thedry period.
Assignments :1. Explore ways of maintaining organic matter in the soils under mango.
2. Give constraints and possibilities of using suggested IPNS programmes inmango.
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SECTION V
Root and TuberCrops
This section of chapter 4, deals withimportant root and tuber crops, sweetpotato, Cassava, Xanthosoma, ginger andAmorphophallus.
Following are the broadobjectives of this section onroot & tuber crops
1. To provide knowledge on soilrequirements, different ways ofcultivating root and tuber cropsand nutrient removal by selectedtuber crops.
2. To provide information on croppingsystems adopted for different rootand tuber crops and nutrientmanagement practices; both DOArecommendations and farmerpractices.
3. To suggest on IPNS package forthe different root and tuber crops.
Introduction
l Root and tuber crops form animportant part of the Sri Lankandietary habits. They are consumedboiled, baked, fried or made intosweet meats and preserves.
l Root and tuber crops are bothindigenous and introduced. Potato
is one of the most importantintroduced tuber crops.
l Botanically tuber crops are classifiedinto shoot tubers like potato or roottubers like sweet potato or diascoreayams.
l Root crops are suited for mediumand coarse textured soils. Loamysands and loamy soils are best suitedfor their cultivation.
l These crops are grown under diverseconditions of uplands, modifiedpaddy lands and under coconuts.Good drainage, soil fertility, soildepth and absence of gravel facilitateits cultivation. Adequate amounts oforganic manure is necessary for theimprovement of soil physical andchemical characteristics.
l Root and tuber crops are classifiedbroadly under the followingcategories.
Local name Botanical name
Potato Solanam tuberosum
Innala Coleus rotandus
Cassava Manihot utilisima
Sweet potato Ipomea batata
Kiriala Xanthosoma sppGahala Alocasia spp
Ginger Zingiber zeylanica
Diascorea yams Diascorea alata
l All root and tuber crops are heavyremovers of plant nutrients. (Table16). Thus a balanced fertilizerprogramme should be followed tosustain production.
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Table 16: N, P and K removed by some common root and tubercrops.
l Intercropping of coconut palms canbe done when the palms are lessthan 5 years old and when palmsare over 40 years of age. Moisturecontent of the coconut lands areimportant to manage both conditionsfor optimum results.
See DOA fertilizer recommendationfor Root & Tuber crops
1. POTATO (IRISH POTATO)
l Could be grown successfully in theAgro ecological zones of the upcountry wet zone (WU), up countryintermediate zone (IU) and also oncoastal beach sands and well drainedRed yellow latasols of Jaffna. It couldbe grown on other soils but thelimitations are the prevailence ofbacterial wilt and early and late blight.
l Requires a well drained loamy tosandy loam soils. Often heavytextured soils are added with largeamounts of organic manure toartificially change the texture.
l Potato fits into various croppingsystems
i. Potato – Vegetable system
ii. Rice - potato system
iii. Red onion - Vegetable - potatosystem
l It is grown both on uplands and welldrained paddy lands withsupplementary irrigation.
l Farmers add heavy doses of organicmanure as wet cowdung grassmixtures or poultry litter. The rates ofaddition vary from 20-60 t/ha forcowdung mixtures and 05-20 t/hafor poultry litter.
l Over addition of chemical fertilizersand sometimes Mg and foliarapplicants are carried out.
l Liming of soils are not done forpotato but usually it follows acabbage crop which has been limedthe previous season. This practice iscommon in the Nuwara Eliya district.
Recommended practices
l Follow soil test based fertilizerrecommendations.
l Use straight fertilizers to avoid buildup of nutrients.
l Overuse of chemical and foliarnutrient applications results in thepollution of soil and the water ways.
Crop Yield (t/ha) Nutrient removal (kg/ha)
N P2O5 K2O
Cassava 30 180 22 160Sweet potato 20 123 15 175Amorphophallus 36 121 23 176D. alata 25 163 30 126Coleus 26 106 13 107
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l Control of erosion of soils is importantto retain soil fertility as well as toprevent sedimentation of waterwaysand possible eutrophicafion of waterreservoirs.
l Crop rotation to prevent cystnematode build up should bepracticed.
l Use cattle manure or poultry manureas organic sources.
2. SWEET POTATO
l Sweet potato is extensively grown inrice based cropping systems in theGodakawela – Ambewila area of theRatnapura district and in Rajanganein the Anuradhapura district and alsoin some parts of the Puttalam andKegalle districts.
Fig 38: Sweet Potato covers soil well
l It is also cultivated on uplands andin 'Ovita' soils of the well drainedpaddy lands.
l Sweet potato is extensively cultivatedin the coastal beach sands ofKalpitiya in Puttalam and in Kinniyain the Trincomalee district.
l Addition of organic manure is carriedout by farmers of Kalpitiya andKinniya but most other farmers relyon added chemical fertilizers of whichthe NPK mixtures recommendedfor rice and potato are often used.
Recommended practices
l Addition of adequate amounts oforganic manure and compost.
l Balanced fertilizers with NPKfertilizers.
l Soil test based fertilizer usage.
l Crop rotation to avoid pest anddiseases and excessive build up ofnutrients.
3. INNALA
l Innala is extensively grown in ricebased cropping systems.
l During the yala season in theGodakawela area.
l During the maha season in theElpitiya Bentara area.
l They are grown on raised beds withwater allowed to seep into the beds.
l Farmers add NPK mixtures as abasal dressing and urea or NKmixtures as top dressings.
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l Use of organic manure as cowdung,green manure or poultry litter as abasal application has given highyields.
Recommended practices
l Mixing of organic manure to soilbefore applying basal fertilizers.
l Use of straight fertilizers.
4. MANIOC (CASSAVA)
l It is grown in many parts of thecountry. Can be grown in all soil typesexcept heavy textured soils.
l Crop requires a deep soil withsufficient drainage.
l Is mono cropped both as a rainfedcrop in the uplands of the dry andintermediate zones and wet zone;also as an alternate crop in rice basedcropping systems of the well drainedwet zone.
l Manioc is intercropped with rubberin the early years of the rubber plantsin new plantations and intercroppedwith short annual crops andvegetables.
l It is cropped between coconut trees.
l Farmers of the wet zone districts addorganic manure and fertilizers. Butfarmers of the dry zone rely mostlyon the nutrient available in the soils.
l NPK nutrients are added at the timeof planting or at earthing up.
Recommended practices
l Use of organic manure as cowdung,poultry litter or green manure beforeplanting.
l Addition of crop residues and ricestraw as a mulch.
l Application of recommended ratesof NPK fertilizers.
l Soil conservation after uprooting toprevent erosion and loss of top soil.
l Crop rotation to replenish soils.
5. KIRIALA - XANTHOMONAS/ GAHALA - ALOCASIA
l Is grown as a home garden cropwith minimum attention given to cropnutrition.
l Commercial cultivation is carried outbetween coconut plants and as ayala crop in rice based croppingsystems with supplementingirrigation.
Fig 39: Intercropping Banana with Kiriala
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l Farmers use coconut husks, coir dustmixed with cow dung or poultry litterto fill holes before planting.
l Rice straw and husk are used tocover beds by the Rajanganefarmers.
l NPK fertilizer mixtures meant for riceare added as a basal application.
l Paddy rice NK mixtures are addedas top applications.
Recommended practices
l Conservation of moisture bymulching with leaf litter, coconuthusks or rice straw.
l Application of NPK fertilizers intoholes and mixing thoroughly beforeplanting.
l Application of a balanced mixture offertilizers.
6. DIASCOREA YAMl Growing of diascorea yams as a
mono crop is carried out in smallscale in the Kalutara and Gampahadistrict.
l It is intercropped with onion in theJaffna, Batticalo and Trincomaleedistricts.
l Often grown as a hedge crop in themid country wet zone and under treecover in the low country and midcountry regions.
l Many species of diascorea yams aregrown.
l Farmers add composted materialsor well rotted cowdung to plantingholes.
l Some farmers add NPK mixtures asthe basal application.
l Green leaves are added to mulchthe soils.
Recommended practicesl Conservation of moisture by using
coconut husk, rice straw, greenleaves or leaf litter.
l Application of organic manures of10-15 kg/hole.
Fig 40: Intercropping Coconut with Kiriala
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l Application of recommended rate ofNPK fertilizer as the basal andaddition of NK fertilizer as topdressing.
l Avoid over use of chemical fertilizers.
7. GINGERl Is grown both as a home garden and
as a commercial crop.
l The local and Chinese types of gingerare grown for commercial markets.
l Grown on raised beds undercoconuts and other tall canopiedtrees; or on paddy rice threshingfloors.
l Requires well drained soils as cropis susceptible to water logging.
l Commercial farmers add cowdungand poultry litter on beds to plant therhizomes.
l Mulching with coir dust, rice strawand leaf litter is carried out.
l Farmers add young coconut palmresidues as the basal application andNK rice mixtures as top dressing.
l Often over addition of urea basedfertilizer nutrients is carried out.
Recommended practices
l Application of organic manuresincluding carbonized rice husk.
l Mulching of the crop with suitablemulching materials
Rice straw
Rice husk
green leaves
coconut fronds
l Composting of crop residues.
8. ELEPHANT YAM(Kidaran)Amorphophallus
l If is a crop grown in most parts ofJaffna and on coastal areas ofTrincomalee, Batticaloa etc. Alsogrown in some parts of Hambantotaand the Monaragala districts.
l Farmers who grow a commercialcrop add high doses of organicmanure as cowdung, goat dung orcompost to each hole.
l Some farmers use NPK nutrients.
Recommended practices
l Mulching to conserve soil moisture,material suggested under diascoreayams could be used.
l Application of recommended NPKfertilizer.
Assingments1. List Root and Tuber crops grown in your area and give different cropping
systems adopted for these crops.
2. Study IPNS practices done in intercrops of your area and find strengths andweaknesses of the practices.
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Appendix 1.
Deficiency and toxicity symptoms caused bydifferent nutrients in rice plant
Phosphorus deficiency
Potassium deficiency
Iron toxicity
Sulphur deficiency
Source: IRRI
124
Appendix 1a.
Deficiency symptoms caused bydifferent nutrients in Maize
N deficiency
N deficiency
K deficiency
P deficiency
Source: DOA
125
Appendix 2.
Fertilizer standards based on Sri Lanka Standards Institute (SLSI)
a). Urea SLS 618: 1983
General Requirements
l Material shall be in the form of prills or crystals and shall be free from visibleimpurities and dust.
l Prilled urea shall pass through a sieve of 2.36 mm square.
l Other requirements
Characteristic Requirement
i. Maximum moisture % by mass 1.0ii. Total minimum N% by mass 46.0iii. Biuret % by mass, maximum 1.0
l Packaging : Polypropylene or jute bags with inner lining
l Marking : a. Urea, fertilizer grade in capital letters
b. Manufacturer’s name and address
c. Registered trade mark if any
d. Net mass in kg.
e. Batch or code No.
f. Date, month and year of manufacture
g. % by mass of total N content.
b. Ammonium Sulphate SLS 620:1983
General Requirements
Material shall be in the form of crystals, usually colourless, and free from visibleimpurities.
Other requirements
Characteristics RequirementMoisture % by mass maximum 1.0Total N % by mass minimum 20.6Free acidity (as H2 SO4)% by mass, maximum 0.025Arsenic (as AS2 O3)% by mass maximum 0.01
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Packaging and making as for Urea.
c) Triple Superphosphate SLS 812 :1988
General requirements:
Material granular and free flowing, free from lumps and visible foreign matters.
Particle size
100% of the material by mass should pass through a sieve of 4.75 mm square.
Other requirements
Characteristics Requirement
Moisture % by mass max 4
Total phosphate (as P2 O
5)% by mass minimum 46.0
Water soluble phosphates (as P2O5) minimum (% of total) 80.0
Free phosphoric acid maximum (as P2O
5) 3.0
Packaging is as per urea.
d. Potassium Chloride SLS 644: 1984
General requirements
Material shall be crystalline and white, light gray or pinkish in colour. Free ofimpurities of clay or grit.
Other requirements
Characteristics Requirement
Moisture % by mass, maximum 0.5
Potash content (as K2O) % by mass minimum 60.0
Sodium (as NaCl) % by mass maximum (on dry basis) 3.5
Packaging and marking as per urea.
Source: Sri Lanka Standards Institute
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Appendix 3.
Available plant species as green manure in the LCDZ and LCIZ
Plant species Plant family Local name
Aleurites moluccana Euphorbiaceac Kekuna
Alstonia macrophylla Apocynaceae Hawarinuga
Barringtonia recemosa Lecythidaceae Midella
Cebera manghas Apocynaceae Mudu-Kaduru,GodaKaduru
Croton lacciferus Euphrobiaceae (Leguminosae) Keppetiya
Curcuma zedoaria Zingiberaceae Harankaha
Datura metel Solanaceae Anththana
Erythrina sp Fabaceae (Leguminosae) Erabadu
Gliricidia sepium Febaceae (Leguminosae) Wetahira, Sewana
Jatropha curcas Euphobiaceae Wetaedaru
Manihot glaziovii Euphobiaceae India Rubber
Manihot sp. Euphobiaceae Alimannokka
Melia dubia Meliaceae Lunumidella
Michelia champaca Mangokiaceae Sapu, Gini sapu
Micolossa ceylanica Asteraceae (Composiae) Pupala
Mikania cordata Asteraceae (composistae) Watu-palu, Gahala-wel
Oroxylum indicum Bigoniaceae Totilla
Pagiantha dichotoma Apocynaceae Dee-Kaduru
Pavatta indica Rubiaceae Pavatta
Pongamia pinnata Fabaceae (Leguminosae) Karanda,Mangulkaranda
Premna tomentosa Verbenaceae Seru
Samanea saman Mimmosaceae (Leguminosae) Mara
Tephrosia purpurea Favaceae (Leguminosae) Pila
Thespesia populnea Malvaceae Gansooriya, Sooriya
Tithonia diversifolia Asteraceae (Compositae) Naththasooriya, Tiththa
Wickstroemia canescens Thymelaeceae Nahadunu, Maha patta
128
Appendix 4.
Different types of livestock populations in the country by districts
District Buffalo Cattle Poultry Goat Sheep Pigs
Colombo 13100 23300 862100 6100 0 6500
Gampaha 22200 51700 1227300 16900 100 19700
Kalutara 29900 40800 705100 14600 0 3700
Kandy 20400 58100 679400 29800 0 600
Matale 25700 50000 198300 13900 0 1700
Nuwara Eliya 6000 51600 178800 14500 200 400
Galle 12800 27100 279900 7300 0 400
Matara 10700 32700 146400 3900 0 100
Hambantota 59900 78800 112100 15500 0 1200
Jaffna 0 58300 274700 38700 3900 0
Kilinochchi 1400 17300 63400 14100 3200 200
Mannar 4700 50300 64600 9800 0 100
Vavuniya 1000 26700 55400 5300 0 0
Mullativu 6300 39400 79000 11300 300 200
Batticaloa 52700 121800 244700 31800 0 100
Ampara 33800 100900 273300 12400 0 100
Trincomalee 47900 75900 157600 21400 100 100
Kurunegala 142700 197500 1886100 58500 2000 9300
Puttalam 16000 92500 796100 52600 1400 18400
Anuradhapura 84500 147100 288700 42700 500 5500
Polonnaruwa 41300 48000 17400 14200 0 1900
Badulla 8300 80800 202100 20300 100 300
Moneragala 25000 67500 99500 4900 0 100
Ratnapura 19800 35400 198500 31700 0 2700
Kegalle 16600 24100 237800 22300 0 2000
Mahaweli ‘H’ 6500 15400 59800 4300 0 1000
Source : Department of Census and Statistics, 1999
129
Appendix 5.
Organic materials and their nutrient composition
(a) Green ManureBotanical Name Common Name % oven dry basis
N P K C:N1. Trees whose leaves are usedAleurites triloba Telkekuna 2.34 0.17 2.65 19Azadirachta indica Margosa 2.38 0.20 1.30 20Borassus flabellifera L Palmyra 1.62 0.10 1.07 32Cerebera adollam Kaduru 2.31 0.10 1.80 22Erythrina lithosperma Dadap 4.00 0.29 3.95 14Gliricidia maculata Madera 4.15 0.27 3.00 12Tamarindus indica Tamarind 1.59 0.19 1.19 27
2. Plants whose leaves and stems are usedCalotropis gigantea (L) Ait.f Wara 3.86 0.30 3.45 11Cassia occidentalis Penithora 4.91 0.20 1.87 12Croton lacciferus Keppetiya 3.50 0.30 2.15 15Tephrosia purpurea Pita 3.73 0.28 1.78 11Thespesia populnea Suriya 3.43 0.25 3.30 14Tithonia diversifolia Wild sunflower 3.84 0.29 5.90 14
Source: Nagarajah, S. and Amarasiri, S.L. (1977)
(b) Crop Residues
Materials Nutrient content (% oven dry basis)
N P KBean straw 1.57 0.32 1.34Cowpea stems 1.07 0.14 2.54Maize stover 0.70 0.06 1.19Rice straw 1.10 0.16 1.40Sugarcane trash 0.35 0.04 0.50
Source: FAO
(c) Wood wastes
Materials Nutrient content (% oven dry basis)
N P KSaw dust 0.12 0.02 0.06
Source: FAO
130
Materials Nutrient content (% oven dry basis)
N P K
Buffalo dung 0.75 0.2 2.0
Cattle dung 1.83 0.49 1.62
Cattle urine 2.5 0.05 2.12
Goat dung 1.33 0.30 1.39
Pig dung 2.82 1.17 1.49
Poultry manure 3.33 1.36 1.80
Farmyard manure (FYM) 0.80 0.18 0.61
Rural compost 1.12 0.42 1.22
Urban compost 0.57 0.62 1.16
Source: FAO
Excreta output of Livestock
Species Average Daily Excreata output (per individual)
Body weight (kg) Wet weight (kg) Volume (m 3)Buffalo 372.2 12.2 0.024
Chicken 2.05 0.1 0.0001
Cow 306.7 11.6 0.021
Sheep 32.5 0.76 0.0012
Swine 71.2 2.9 0.0043
Source: Department of AP & H
Appendix 5. (contd.)
Organic materials and their nutrient composition
131
Appendix 6.
Agro - Ecological Regions of Sri Lanka
Source: NRMC,Department of Agriculture
132
Appendix 6. (Contd.)
Source: NRMC,Department of Agriculture
133
appendix 7.
Nutrient removal by vegetables total and edibleportion at harvest
Crop Yield Primary Nutrients Secondary Micro-nutrients
(t/ha) (kg/ha) Nutrients (kg/ha) (g/ha)N P K Ca Mg Cu Zn Fe Mn
Beet 52 139 20 171 29 9 90 172 2397 442
Leek 44 132 18 242 31 24 71 511 2614 906
Spinach 16 58 9 88 41 17 89 62 3371 371
Lettuce 10 16 2 23 5 2 9 35 430 46
Sweet Potato (T) 23 48 13 83 10 5 26 14 416 70
Sweet Potato (Total) 108 20 207 23 15 58 38 2147 255
Radish 35 73 11 118 42 11 25 112 1295 241
Cabbage 60 128 18 175 60 14 44 188 1365 382
Bittergourd (P) 30 80 12 88 6 10 83 13 447 113
Bittergourd (Total) 130 19 148 30 21 127 150 1563 281
Luffa (P) 30 41 9 54 5 5 32 53 626 58
Luffa (Total) 151 24 169 97 33 118 218 3198 342
Snakegourd (P) 30 40 6 52 17 7 55 55 492 103
Snakegourd (Total) 73 10 89 38 14 93 96 1256 285
Bean (P) 12 39 6 39 5 4 23 60 544 131
Bean (Total) 166 19 143 86 19 106 388 3831 1606
Okra (P) 18 59 9 76 15 10 50 87 455 158
Okra (Total) 95 14 131 62 24 86 172 1357 553
Capsicum (P) 10 25 2 14 9 5 18 20 147 44
Capsicum (Total) 67 5 63 23 9 56 70 1074 208
Brinjal (P) 25 57 9 74 1 6 47 162 153 37
Brinjal (Total) 130 18 241 58 21 141 251 571 210
Potato (T) 20 38 7 81 3 4 32 153 652 89
Potato (Total) 222 27 479 71 24 105 541 10546 2506
Tomato (F) 25 127 14 165 10 9 176 129 4103 126
Tomato (Total) 163 18 206 42 20 346 222 7709 344
Carrot (T) 31 70 14 104 23 10 53 158 1491 267
Carrot (Total) 159 24 237 52 20 114 430 3693 699
F = fruit; P = pods; T = tuber
Source: Amarasiri and Wijesundara
134
Appendix 8.
METHODS OF COMPOST MAKING.
There are several methods of compost making that are easily carried out by the farmers.The type of method to be selected depends on the following.
l Climatic conditions.
l Amount of waste material available.
l Type of waste materials.
l Demand for compost
l Labour, land, availability.
l Scales of operation
l Targeted use
l Generally climatic conditions, of extreme dry, wet and cooler climates reduces thechances of obtaining good composted material within a desired time.
l The amount of waste material availability from homesteads, gardens and citiesdecides on the type of composting method to be followed.
l Type of waste materials like city garbage, crop residues and FYM are important indeciding the methods of composting.
l The demand for compost, for own use or commercial purposes has to be decidedin selecting the method.
l The land and labour availability decides on the type of system to be utilized. Forurban home gardens barrel method is preferable.
l Commercial compost making requires rapid methods of composting.
l The targeted area, for food crops. ornamental plants decides on the type of compostto be used.
Material available for Compost making.
l Any biodegradable organic material found in nature or a byproduct of agro-basedindustries could be composted.
l Materials found common in homes like kitchen waste, garden refuse, leaf litter,animal dung could be used for composting.
l City garbage, slaughter house waste, wastes from timber mills, rice mills etc. couldbe composted.
l Crop residues, FYM, green leaves and stems are available in farms for composting.
135
Materials required for Composting.
l Composting requires materials of both high C:N and low C:N material to effect thebio degradation and to reduce loss of N.
l Requires 35-45% water by weight of the waste material.
l Requires a control environment to effect the bio degradation by microbial action.
Precautions necessary in composting.
l Care should be taken to avoid metallic substances to get into the compost piles.
l If human faecal materials are found in the waste thermal methods of compostingshould be carried out to prevent the spread of diseases.
l City garbage should always be composted using aerobic methods
TYPE OF COMPOSTING METHODS.
There are two major types.
l Aerobic
l Anaerobic
AEROBIC METHODS
Aerobic methods allow the microbial forms usingoxygen to carry out the biodegradation.
There are many methods followed under aerobicmethods. For small home gardens. Barrel or Bamboo- cage method could be used conveniently.
Barrel Method
A barrel as shown in the diagram (1) is cut openedat the bottom . House waste material are added fromthe top and compressed by a stick. The top is coveredby a lid to prevent flies. As the barrel gets filled dueto the pressure from the top composted material willflow out the vents due to pressure brought by the stick.
l There is a possibility of introducing earth wormsto the barrel, compost made is of high quality.
Diagram 1 - Barrel Method
136
Bamboo Cage Method
This is similar to Barrel method. Operations are done as in Barrel method. Compostedmaterial could be removed from the space between bamboo sticks. see digram (2)
Heap Method
This method could be used for preparation of compost infairly large quantites. see digram (3)
The size of the heap should be decided on
lAmount of waste material available
l Labour availability
lRainfall patterns.
In using Heap method the following should be considered.
lRemoval of bottles, metalic items, plastic andpolythene material.
lCutting of material into smaller pieces andspreading
l Laying of high C:N material like grass/strawalternate with low C:N material like tendershoots/cowdung
lAddition of innoculum obtain fro a composted material orcowdung slury.
l Addition of water to saturate each layer
l Compacting each layer
l Covering up of the heap by blackpolythene or a mud film.
Where city garbage is used more aerationshould be allowed, (eg. Chinese method)
l Earth worms could be introducedto the heap after cooling.
l The turning of the heap be carriedout at 2 weeks, 4 weeks and 6weeks interval.
l The composted material isavailable in 12-14 weeks.
l The composted material should beair dried, pounded and sievedbefore marketing.
l Heap method is more suited inareas with heavy rain.
Diagram 2 - Bamboo Cage Method
Diagram 3- Heap Method
137
Pit method
l Is an inverted heap method,more suitable to dry areas. Abund should be put round thepit to avoid seepage of waterinto the pit. A roof is required tokeep off the rain. See digram(4). Procedure followed in HeapMethod is practiced to fill thepit.
Digram (4a) - Pit method
Digram (4b) - Pit method
1. Silt straw mixture 2. Green manure (e.g. Gliricidia) 3. Stable manure (Cowdung)
Rapid method of Composting
For rapid decomposition a mixture of organic residues in the proportion of two parts ofcarbon rich material like straw, saw dust are mixed with one part of N rich material likelegume leaves or animal dung. The leaves are shredded into smaller size and mixedthoroughly with the dung. This materials are heaped for two weeks. The turning shouldbe done on the fourth, seventh and tenth day. Sufficient water has to be added initiallyand at each time of turning. The compost is ready after two weeks from the time of initialheaping.
15 cm. each2.0
m.
1.5
m.
3.5 m.
2.5
m.
3.0 m.
123123
138
High temperature compost. (Chinese method)
This method is suitable for composting material which could contain harmful parasitesand pathogens which can affect human and animal health. It is ideal for composting urbanwastes and animal wastes.Materials which are coarse andhigh in C/N ratio are laid in layerssimilar to that in the heap methodand followed on top by moresucculent material or animaldung, market refuse, slaughterhouse refuse etc. This pilingsystem is carried out until amaximum height of 1-1.5 m isreached.
At the time of making the heap a series of bamboo poles (septa broken) or PVC tubes5 cm diameter are inserted for aeration purposes. See digram (5) After the heap formationis completed it is covered with black polythene or by a mud paste. Weights are kept onthe top of the heap. Water in sufficient quantities are added at the time of piling up. Thebamboo poles PVC tubes are withdrawn in 2-3 days, leaving the holes to remain. Afterfour to five days the temperature rises to 60-70 Co and the holes are sealed off. Thefirst turning is done after two weeks and water is added in sufficient quantities to moistenthe material. This is again heaped up and sealed with mud or covered with black polythene.Two more turnings are done at 4 weeks and 6 weeks. The compost is ready in 8 weeks.
ANAEROBIC METHODS
No air is allowed into the system and microbes uses other sources of material to breakdown complex organic forms. eg. Bio gas production. As air circulation is cut off, partialdecomposting take place. The pit method of composting if covered by a layer of animalurine will result in the anaerobic decomposition of material which will be ready as compostin 6-8 months.
Bio-gas preparation results in anaerobic decomposition. Methane, carbon dioxide andhydrogen sulphide gases are produced. The bio-gas slurry forms a suitable material foraddition in crop husbandry.
Continuous Supply of Compost for Crop Production.
A series of heaps or pits has to be organized if a continuous supply is necessary. Thiscould be worked out for disposal of urban refuse.
Digram (5) - High temperature compost.
139
Nature and Properties of finished composts.
The finished compost should have the following features:
(i) Dark brown to black in colour.
(ii) Practically insoluble in water.
(iii) Has a C/N Ratio ranging from 10 to 20.
(iv) Has a beneficial effect both on the soil and the growing crops.
Precautions necessary in using compost.
Compost made out of city garbage may carry,
l Heavy metals of Arsenic, Lead, Cadmium and mercury are extremely harmful toboth humans and domestic animals.
l Harmful to humans and animals. Pathogens of diseases of Enteritis, Tuberculosisetc, Pathogens could be found in city wastes. Since their thermal death points arespecific, care should be taken to allow the heating up of heaps.
Note: For additional reference see DOA publication on Organic manure usage.
140
App
endi
x 9.
EC
ON
OM
ICS
OF
IP
NS
Cro
p: R
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Pro
duct
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area
: 40
00 m
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Tre
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Cos
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Ope
ratio
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Tot
al C
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Fer
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Rs.
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.
No
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1432
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1143
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atio
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has
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R.
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- R
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RH
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